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| wdt_ID | Year | Topic | Location | Contaminant / Issue | Event | Impact | Reference |
|---|---|---|---|---|---|---|---|
| 71 | 2013 | Drinking water | Minnie Waters, NSW, Australia | E. coli found leading to a Boil Water Alert | Minnie Waters is a coastal village of around 250 people located approximately 50km east of Grafton. Following E. coli detections during routine sampling, Minnie Water residents were advised to boil water from 8th February 2013 until 12th February 2013, and then again from the 6th March 2013 until the 13th March 2013. In response to both E. coli detections Council added liquid chlorine to the reservoir, flushed the system, and inspected the reservoir. The first detection was thought to be related to extraction from Lake Minnie Water (the raw water supply) during a high rainfall event, introducing a high organic load to the system. Since that event, the Minnie Water scheme has selective extraction, where operators cease extraction during extreme wet weather events. For the second event, there was no obvious contamination source. The top section of the reservoir is mesh and it is thought that during a significant East Coast Low event with both heavy rainfall and gale force winds, contaminated stormwater runoff from the roof was blown back into the reservoir through the mesh. | 250 customers on boil water alert for 4 days | Greg Mashiah, Manager Water Cycle, Clarence Valley Council pers. communication. February 2016. |
| 206 | 2011 | Drinking water (backflow) | The Gap, QLD, Australia | Fire Retardant | In September2011, residents alerted Queensland Urban Utilities that foamy water was running from their taps. Previously Queensland Fire and Rescue had attended a house fire located on Dungory Street. How the foam had entered the distribution system was unknown. RISK EDGE NOTE: Backflow events have been the cause of some important waterborne contamination incidents. This event highlights the impact that external stakeholders can have on the production of safe reliable water services. Training and creation of water quality awareness, is an informative control that you can apply, to help prevent or decrease the likelihood, of a water quality event happening. Once people understand the "why", it often cements the "what" of their roles. |
387 houses were affected and provided with bottled water | ABC News |
| 211 | 2024 | Public pools and water parks | NSW, Australia | Cryptosporidium | Significant uptick in cryptosporidiosis, a diarrhoeal disease caused by the gut parasite, Cryptosporidium. The disease is usually caught when people swim in or swallow water contaminated with the parasites. Inhaling contaminated water, can also be a source of infection, but is not as common. Symptoms of cryptosporidiosis include acute diarrhoea, nausea, vomiting, fever, headache and loss of appetite. The cause of the increase is not fully understood but may be weather-related. Young children are particularly vulnerable. Anyone who has the illness should stay away from public pools for at least two weeks. |
498 recorded disease cases in NSW so far this year, a nearly 500% increase from the previous five-year average (95 cases during the same time period). |
ABC News NSW Health |
| 235 | 2024 | Drinking water | Brixham, Devon, UK | Cryptosporidium (protozoan) | Update June-July 2025: South West Water, owned by Pennon Group, reported that the incident cost nearly £40 million, including £16 million in compensation to affected customers and £4 million for infrastructure improvements. Pennon also reported pre-tax losses of £38.8 million in the six months to September 2024, compared to £34 million in the same period the year before. During this time, the company completed a £380 million takeover of Sutton and East Surrey (SES) Water. South West Water customers are set to face a 23% increase in bills over the next five years to fund infrastructure upgrades and reduce pollution incidents. The incident prompted political scrutiny and public criticism, leading to a public apology from the company’s chief executive. 14 June 2024: Over a month after the detection of Cryptosporidium in the water supply, more than 2,000 homes in Brixham are still under a boil water notice. Although the notice was lifted for 21 households on June 14, 2,073 households remained affected. South West Water continues to monitor and clean the network. Incidents Online will continue to monitor this case as it highlights the need for maintenance programs, understanding of system context and risk, incident and emergency management procedures and community consultation. 15 May 2024: A health alert occurred, due to numerous residents falling ill with suspected cryptosporidiosis (severe stomach pain and diarrhea, with symptoms lasting one to two weeks). South West Water originally reported all water quality tests were clear. However, local residents reported widespread illness, prompting concerns about water quality despite reassurances from authorities. South West Water has since confirmed the likely cause of the event as a defective air valve, allowing ingress of contaminated water to their distribution system. RISK EDGE NOTE: Water should not be forgotten once it has left the treatment plant. There are still many exposure pathways by which the water may become contaminated or conditions occur which allow hazards (such as free-living amoebae and Legionella) to proliferate, and make the water unfit for consumption. This event underscores the importance of understanding your distribution system, where your assets are, what condition they are in, and making sure your process flow diagram is correct. A risk context review, including sanitary survey and flow diagram review, should be undertaken prior to every water quality risk assessment to ensure uncertainties are identified and addressed. |
Update June-July 2025: Hundreds of people fell ill, with hospitalisations reported. Boil water notices issued to approximately 17,000 households and businesses for up to eight weeks. South West Water incurred nearly £40 million in response costs. 14 June 2024: >2,000 homes in Brixham are still under a boil water notice. The outbreak has also hurt the local economy due to lost tourism. 15 May 2024: Social media reports suggested "hundreds" were affected. UK Health Security Agency confirmed 46 cases. |
Update June-July 2025: ITV News West Country Original: Torbay Weekly Manchester Evening News Alert via Steve Atchison, Schedulista BBC News Update alert courtesy Adrian Thompson |
| 266 | 2024 | Asset protection (backflow devices) | Tampa, Florida, USA | Water infrastructure security | Theft of backflow prevention devices in Tampa, Florida, poses risks to public health and safety. Without these devices, contaminated water could flow back into the main distribution system, leading to potential drinking water contamination. Missing devices may also disable fire sprinklers in affected properties, increasing fire hazards. Thieves are targeting these devices for their brass components, which can be sold as scrap metal. This issue is exacerbated by the high visibility of backflow devices along Tampa’s roads, making them easy targets for theft. Over 40 backflow prevention devices have been stolen in 2024, surpassing theft numbers from prior years. The Tampa Water Department and local plumbers are raising awareness of the issue, emphasizing the high replacement costs and potential risks of contamination or loss of fire protection. RISK EDGE NOTE: Backflow events have been the cause of some important waterborne contamination incidents. Theft in Australia is also known to occur (Peter McLennan, CEO Backflow Prevention Association of Australia; pers comm). Given the criticality of water supply assets and obligations under the Security of Critical Infrastructure Act 2018 (Cth), it is essential that appropriate risk management is put in place for not only installation, but also, protection during a backflow protection device’s lifespan. |
Over 40 backflow prevention devices stolen | 10 Tampa Bay Alert courtesy Adrian Thompson |
| 314 | 2024 | Drinking water contamination (cross-connection, backflow) | Bay County, Florida, USA | Sanitary sewer line connected to potable water line | In December 2024, Bay County officials issued an immediate advisory to RiverCamps subdivision residents to stop using potable water after discovering that a contractor had mistakenly connected a sanitary sewer line to the potable water line. The cross-connection occurred approximately three weeks before the issue was identified, leading to water contamination concerns. Bay County Utilities resolved the issue and began flushing the water system aggressively. Bottled water was distributed to affected residents while bacteriological sampling was conducted to confirm the water's safety. RISK EDGE NOTE: We've been in water risk assessment workshops where people have categorically said that this type of event could never happen. That is why we always do a "risk share" at the beginning of our risk workshops and alert people to what could occur and to help them think a bit more broadly. It's also helpful to look at other industries to see if anything has happened elsewhere that could help identify any uncertainties risk assessed. It's also part of the reason that we made our Incidents Online freely available, as a learning tool that will hopefully help to prevent similar incidents. This event highlights the impact that external stakeholders can have on the production of safe reliable water services. training and creation of water quality awareness, is an informative control that you can apply, to help prevent or decrease the likelihood, of a water quality event happening. Once people understand the "why", it often cements the "what" of their roles. Contact us if you would like to know more about our course "Fundamentals of Backflow Prevention: Its Role in Achieving Safe, Reliable Water", created in conjunction with the Backflow Prevention Association of Australia. |
Disruption to access to drinking water. Potential for serious waterborne outbreak. Costs of flushing and distribution of bottled water to affected residents. |
WJHG News Alert courtesy of Adrian Thompson |
| 316 | 1981 | Drinking water contamination (backflow) | Bangor, Maine, USA | Antifreeze discovered in a homeowner’s water supply. | During repairs, Bangor Maine Water Department employees shut off the service line to a home, causing a pressure drop in the internal plumbing. This allowed antifreeze, previously added to an unused hot water heating system, to backflow into the home's water lines and toward the street. If unnoticed, the antifreeze would have entered the house drinking water supply when pressure was restored, posing significant health risks. RISK EDGE NOTE: This incident highlights the critical need for backflow prevention devices and proper cross-connection controls in residential systems. Implementing backflow prevention measures, such as check valves or air gaps, could have prevented the antifreeze from contaminating the water supply. Regular inspections and homeowner education on the risks of cross-connections and the importance of backflow prevention are essential to safeguard water quality. Ensure that the maturity of backflow prevention is reviewed at your next water quality risk assessment. The incident also highlights the diligence and importance of trained operations staff. Contact us if you would like to know more about our course "Fundamentals of Backflow Prevention: Its Role in Achieving Safe, Reliable Water", created in conjunction with the Backflow Prevention Association of Australia. |
Operational disruption in remediating the situation. | US EPA Cross-Connections and Backflow Prevention Issue Paper 2001 |
| 318 | 1978 | Drinking water contamination (backflow) | South Carolina, USA | Chlordane (chemical) | Chlordane, a pesticide, backsiphoned from an exterminator truck into the water supply during meter repairs. While a professional exterminator was treating a church for termites and pests, chlordane was mixed with water in buckets using garden hoses submerged in the chemical solution. At the same time, water department personnel disconnected the parsonage’s water line from the church to install a separate water meter, shutting off water to the area. The church, located on a steep hill, experienced negative pressure as water was used elsewhere, causing the chlordane to siphon into the church’s water lines. The contaminated water mixed with Kool-Aid being prepared for vacation bible school. As a result, about a dozen children and three adults suffered dizziness and nausea, though no one required hospitalization. RISK EDGE NOTE: This incident highlights the critical need for backflow prevention measures and proper cross-connection controls to safeguard water systems during maintenance. Installing backflow preventers, such as vacuum breakers or air gaps, at hose connections would have prevented the toxic chemical from entering the water lines. Additionally, ensuring coordination between water department personnel and local establishments before shutting off water, along with educating facility operators and maintenance teams on the risks of submerged hoses, could have mitigated the risk of contamination. Ensure that the maturity of backflow prevention is reviewed at your next water quality risk assessment. Contact us if you would like to know more about our course "Fundamentals of Backflow Prevention: Its Role in Achieving Safe, Reliable Water", created in conjunction with the Backflow Prevention Association of Australia. |
Fifteen people became ill. | US EPA Cross-connection Control Manual 2003 |
| 319 | 1984 | Drinking water contamination (backflow) | Farmington, New Mexico, USA | Sodium dichromate (Backflow of a heating system) | In June 1984, a high school in Farmington, New Mexico, was shut down after a teacher noticed yellow-colored water coming from taps. Testing revealed dangerously high levels of chromium (700 ppm), far exceeding the safe limit of 0.05 ppm. The source of contamination was sodium dichromate, a highly toxic anti-corrosion chemical used in the school's heating system. The chemical entered the drinking water due to faulty check valves on the boiler feed lines, allowing backflow into the potable water system. Fortunately, the contamination was detected before anyone consumed the water. Immediate actions were taken, including covering water fountains and alerting local hospitals to monitor potential symptoms. RISK EDGE NOTE: This incident underscores the importance of backflow prevention as a crucial component of public health protection. There have been numerous examples of backflow-related incidents, so much so that backflow prevention is usually included in plumbing and building regulations, standards and codes. Contact us if you would like to know more about our course "Fundamentals of Backflow Prevention: Its Role in Achieving Safe, Reliable Water", created in conjunction with the Backflow Prevention Association of Australia. |
The school remained closed for several days. The faulty check valves were replaced with proper backflow preventers. The incident underscored the need for strict cross-connection control. |
Watts (Stop Backflow News! Case Histories & Solutions, see p. 24) Schwindt, D. (January, 2025) Alert Courtesy Darryl Schwindt |
| 328 | 2025 | Facility management, Drinking water contamination | Halifax Regional Municipality (HRM), Nova Scotia, Canada | Unchlorinated water entering the drinking water supply | On January 21, 2025, Halifax Water issued a boil water advisory for large portions of the Halifax Regional Municipality (HRM) due to the possibility of unchlorinated water entering the system. The issue originated from the J.D. Kline (Pockwock Lake) Water Treatment Facility, where an external power outage caused the plant’s generator to activate. However, when power was restored, a blown fuse prevented the final step of chlorine treatment, allowing unchlorinated water to flow into the system. Halifax Water could not confirm how much untreated water had entered the supply. The advisory affected residents in Beaverbank, Middle and Lower Sackville, Fall River, Upper Hammonds Plains, Bedford, Halifax, Timberlea, Spryfield, and Herring Cove. The boil water advisory applied to all consumption-related activities, including drinking, cooking, making ice, preparing infant formula, and brushing teeth. Halifax Water stated that a new automated chlorine redundancy system, which could have prevented the issue, was scheduled for completion in just a few days, but the failure occurred before its activation. RISK EDGE NOTE: Whenever an event such as this occurs, one thing your regulator will always ask you is how much water was unfit and where did it go. It is really helpful to have all this information to hand including having done hydraulic surveys, making sure your flow diagrams are up to date, your contact lists are up to date, and your incident and emergency management plan has been tried and tested. A debrief and root cause analysis is also essential once the event has been stood down and closed out. |
Boil water advisory applied to multiple communities. Potential acceleration of water system upgrades. |
PNI Atlantic News Alert courtesy of Stephen Mallette |
| 389 | 2025 | Facility management (Drinking water system) | City of Marlin, Falls County, Texas, USA | Water treatment system failure | On 3 May 2025, Texas Governor Greg Abbott issued a disaster declaration for the city of Marlin following a prolonged failure of the city’s water treatment system. The declaration enabled access to emergency resources and regulatory flexibility to expedite restoration efforts. According to officials, the crisis began in late April, leaving residents without running water for several days. The city issued a boil water notice on 29 April, instructing residents to boil water for consumption and hygiene. Although the exact cause of the failure remains under investigation, local officials suggested that a series of power surges may have damaged the treatment plant’s computers and equipment. In response, the Texas Division of Emergency Management deployed 20 pallets of bottled water, potable water tankers, support staff, and the Texas A&M Public Works Response Team. On 30 April, schools in the Marlin Independent School District closed due to the outage. In an emergency session on 4 May, the Marlin City Council approved $200,000 to procure two portable water treatment units, which were expected to be operational within 24 to 36 hours after setup. The temporary systems were authorised for up to 30 days under the governor’s order. Water towers across the city also required refilling to restore adequate pressure. A public meeting was scheduled to provide residents with updates. RISK EDGE NOTE: This event illustrates the importance of having a tested incident and emergency management plan in place, including the need to understand when to escalate, and bring in external stakeholders. As our water supply systems are increasingly more reliant on automated processes, power management and redundancy for systems are essential controls and need to be prioritised accordingly. Post the incident, there should be a root cause analysis to identify and remedy the causes and avoid a repeat. |
Citywide water outage and boil water notice affecting approx. 5,500 residents. Emergency declaration issued by Texas governor. School closures and emergency procurement of portable water treatment units. Bottled water and tankers distributed; temporary treatment systems authorised for 30 days. |
<a href="https://statescoop.com/marlin-texas-greg-abbott-water-system-failure/" target="_blank"StateScoop Alert courtesy of Glenn Barnes |
| 398 | 2025 | Drinking water | Progreso and Progreso Lakes, Texas, USA | Water treatment plant failure | On 20 May 2025, the Military Highway Water Supply Corporation (MHWSC) issued a boil water notice for the City of Progreso and City of Progreso Lakes after an equipment failure at a local water treatment plant caused a temporary pressure loss. The drop in pressure posed a potential contamination risk and triggered mandatory protocols from the Texas Commission on Environmental Quality (TCEQ). On 21 May 2025, following corrective action and water quality testing, the utility submitted laboratory results to TCEQ confirming the water was safe. The boil water notice was officially rescinded. RISK EDGE NOTE: This event illustrates the importance of having a tested incident and emergency management plan in place, including the need to understand when to escalate, and bring in external stakeholders. Pressure in distribution systems is one of the final measures we have to help keep contamination out of water systems, therefore, having a monitoring plan in place, which measures and signals pressure drops, is essential to maintaining safe, reliable water. Post the incident, there should be a root cause analysis to identify and remedy the causes and avoid a repeat. |
Boil water notice issued for one day. | Fox Rio Grande Valley News Boil Water Notice Rescinded, MHWSC Alert courtesy of Adrian Thompson |
| 406 | 2025 | Drinking water contamination (Recreational Vehicle’s potable water system) | Texas, USA | Naegleria fowleri (amoeba) | In 2025, a 71-year-old woman from Texas developed severe neurological symptoms, including fever, headache, and altered mental status—after using tap water from her RV’s potable water system to rinse her sinuses. She had not been exposed to natural freshwater sources but had used the unboiled tap water on several occasions for nasal irrigation. She was later diagnosed with primary amebic meningoencephalitis (PAM), a rare but fatal infection caused by Naegleria fowleri. Laboratory testing confirmed the amoeba in her cerebrospinal fluid. She died eight days after symptom onset, despite receiving treatment. The RV’s potable water system had been filled prior to her purchase of the vehicle, and the investigation suggested either the storage tank or the connected municipal supply could have been the contamination source. RISK EDGE NOTE: N. fowleri, while extremely rare, is one of those organisms for which climate change may be a concerning factor. As waters heat up, this creates conditions for proliferation of N. fowleri, not just in terms of temperature, but also in terms of disinfectant residuals not lasting as long. If you are responsible for water product safety, or a facility manager, it would be worth undertaking some investigative monitoring of your systems, just to establish a baseline, and to check if you can then see a trend towards warming. Being forewarned is a much better place from which to establish considered risk management actions. If you are using water for public health critical tasks such as contact lens irrigation and nasal irrigation, you need to be absolutely sure that it is disinfected prior to use, water from the tap or stored in your vehicle, is not safe for such purposes. It's also important to remember that tap water is not sterile, it is safe to drink, but not sterile. |
One fatal case (death) of PAM caused by Naegleria fowleri. | NBC News Alert courtesy of Mike McGill and Audrey Killeen |
| 410 | 2025 | Facility management (Drinking water service disruption, healthcare) | Stephens County, Georgia, USA | Water system failure (Plumbing system failure) | On the morning of 21 May 2025, Stephens County Hospital experienced a water system failure due to a malfunctioning pressure reducing valve in its internal plumbing infrastructure. The failure led to elevated water pressure and multiple leaks throughout the facility. Hospital staff responded promptly, containing the water leaks and initiating repairs the same afternoon. Although full hospital operations have since resumed, certain areas, including administrative offices and parts of the emergency department, suffered significant water damage. Restoration work is expected to continue for several months. RISK EDGE NOTE: This event highlights the importance of proactive infrastructure maintenance and monitoring, particularly for internal water systems. It also reinforces the need to understand system flow diagrams during design and planning stages to ensure vulnerabilities—such as pressure control failures—are identified early and mitigated through resilient engineering and operational safeguards. While this event led to a drinking water service disruption, leaks are always a potential exposure pathway for contamination and should be treated as such. |
Internal valve malfunction caused water leaks across hospital premises. Some areas, including administrative offices and parts of the emergency department, experienced significant water damage. |
Now habersham News Alert courtesy of Adrian Thompson |
| 430 | 2025 | Drinking water (distribution reservoir) | Hamilton, Aotearoa New Zealand | E. coli (bacterium) | On Saturday 4 October 2025, Hamilton City Council issued a precautionary boil water notice after routine testing at the Rototuna Reservoir detected a very low level of E. coli, close to the detection threshold. Following consultation with Taumata Arowai, the Water Services Authority, the notice was enacted to protect public health. The reservoir was immediately isolated, and a coordinated response was launched involving multiple agencies and neighbouring councils. No further E. coli detections occurred in subsequent testing across the network and treatment systems. After three days of clear results, the boil water notice was lifted. The exact source of the contamination remains unknown, and no breach of infrastructure has been identified. RISK EDGE NOTE: This incident highlights the importance of conservative decision-making in microbial water safety. Even low-level E. coli detections warrant swift action when public health is at stake. Potential causes may include transient environmental contamination, sampling error, or minor ingress events that self-resolved. Hamilton’s rapid isolation of the reservoir, clear public messaging, and multi-agency coordination reflect strong operational readiness. A root cause analysis remains essential to identify vulnerabilities and reinforce system resilience, even when the source cannot be confirmed. |
Operational impact in dealing with the finding. | Hamilton WSA Stuff NZ Alert courtesy of Sam Wood. |
| 449 | 2025 | Natural seawater contamination Recreational Water | Florida, USA | Vibrio vulnificus (bacterium) | As of mid-July 2025, the Florida Department of Health confirmed that four people had died from infections caused by Vibrio vulnificus, a naturally occurring bacterium found in warm, brackish seawater. A total of 11 cases had been reported in the state so far that year. Vibrio vulnificus infections typically arise via two main exposure pathways: through open wounds when entering contaminated coastal waters (most common), and through consumption of raw or undercooked shellfish, especially oysters. The bacterium thrives in seawater temperatures between 15–40°C, making infections more likely during warmer months, and its proliferation has been linked to climate change and extreme weather events. However, the 2025 cases were not attributed to any recent hurricanes, unlike spikes seen following Hurricanes Ian (2022) and Helene (2024) (see our Risk Edge "bluewashing" white paper for more on this). The Centers for Disease Control and Prevention (CDC) and researchers noted that infections often progress rapidly and can lead to necrotising fasciitis, sepsis, and death if not treated early. Individuals with underlying health conditions, including liver disease, diabetes, or iron overload, are particularly vulnerable. RISK EDGE NOTE: Vibrio vulnificus is a naturally occurring bacterium found in warm, brackish coastal waters. However, its proliferation is strongly influenced by water temperature, salinity, and nutrient levels - factors that can be monitored as part of recreational water quality management. For public health and environmental authorities, or anyone who manages water bodies for recreation, this underscores the need for climate-informed water quality surveillance. Proactive measures such as real-time environmental monitoring, risk-based beach advisories, and targeted public education are critical tools in managing naturally occurring yet predictable waterborne health risks. |
11 cases reported in Florida in 2025 (as of mid-July). 4 confirmed deaths. Previous spikes linked to hurricanes; 2025 cases not linked to any weather event. |
Huffpost News Alert courtesy of Adrian Thompson. |
| 452 | 2024 | Food production Irrigation water management | Multi-state (15 states), USA | Escherichia coli O157 (bacterium) | A multi-state outbreak of E. coli O157 occurred in November–December 2024, affecting 89 individuals across 15 states. Thirty-six people were hospitalised, and one person died. The outbreak was linked to romaine lettuce. In 2025, researchers from Cornell University, Virginia Tech, and the University of Florida published a detailed risk assessment, identifying overhead spray irrigation using untreated surface water as the most likely contamination pathway. The study reviewed previous outbreaks (2015–2021) that caused 4,274 confirmed illnesses, 766 hospitalisations, and 11 deaths. The risk model found that drip or furrow irrigation systems significantly reduced E. coli presence, with up to 96.8% reduction in median illness cases. The study highlighted that water drawn from open canals in California and Arizona (where 90% of U.S. romaine is grown) may serve as a contamination source if not treated. RISK EDGE NOTE: Managing microbial contamination risks in fresh produce requires a supply chain approach that starts at the source. The recent E. coli O157 outbreak and subsequent research show that untreated surface water used in overhead spray irrigation is a critical contamination pathway, while alternative methods like drip or furrow irrigation can reduce illness risk by up to 96.8%. Water is not just an agricultural input—it is a foundational control point for food safety. The Risk Edge Group can help by mapping these upstream vulnerabilities, modelling contamination pathways, and integrating water quality risk into supply chain assessments. This enables producers, regulators, and retailers to prioritise interventions, enforce water treatment standards, and strengthen resilience from farm to consumer. |
89 confirmed cases,36 hospitalisations and 1 death in November–December 2024 outbreak. Study found 52% of illnesses attributable to overhead spray irrigation. |
Food Safety News Full research report Alert courtesy of Food Safety News. |
| 463 | 2025 | Water infrastructure security | Gdańsk, Poland | Water infrastructure manipulation | A cyberattack targeted a Polish hydropower plant, raising concerns about the security of critical water and energy infrastructure. The attackers aimed to disrupt operations and potentially compromise control systems. Russian-linked hackers launched the attack in early January 2025, marking the second time this facility has been targeted. The intrusion focused on industrial control systems, which manage water flow and power generation. Authorities confirmed that the attack was detected and mitigated before causing physical damage, but investigations revealed vulnerabilities in the plant’s cybersecurity posture. RISK EDGE NOTE: Although no service outages occurred, the incident underscores the growing risk of cyber threats to water and energy systems. Such attacks could lead to operational shutdowns, financial losses, and even environmental harm if water releases are manipulated. The event has heightened pressure on operators to strengthen cyber defenses and comply with national security standards.It is important to include cyber security as a line item in risk assessments, to ensure these issues are not overlooked in the risk identification and assessment process. Organisations should regularly check the resilience of their systems with measures such as penetration tests. |
Change of operational parameters causing rotor disruption. | Cybernews. Alert courtesy of Secolve. |
| 477 | 2024 - 2025 | Drinking water contamination Testing protocol failure | Syracuse, New York, USA | Lead (Heavy metal) | In early 2024, the City of Syracuse launched a lead testing program in response to new federal regulations requiring twice-yearly sampling. However, improper sample collection methods, where 66 of 100 required samples were collected by staff (not residents) from outdoor spigots, resulted in exaggerated lead levels in water results. This breached federal protocol, which mandates that residents collect samples from indoor taps. The city initially blamed two staff members, suspended them, and launched an internal investigation. Although city officials later clarified the sampling method was flawed, the incident had already sparked national concern. Activists and media compared the situation to Flint, Michigan, prompting protests and a community forum. Two additional testing rounds, including one by an independent firm, showed lead levels within federal limits. Nevertheless, the incident exposed broader management failures, including weak oversight by the former water commissioner and a delay in updating the city’s required chemical risk management plan. Sampling performed: Round 1 – Early 2024: *104 samples tested. Lead levels reached 70 ppb at the 90th percentile. *This was nearly 5× the federal action level of 15 ppb. *Resulted in EPA inspection, the first in over 10 years. Round 2 – Late 2024 (under new management): *135 properties tested; 9 samples exceeded the 15 ppb threshold. *Re-testing of 23 affected homes from Round 1 found only 1 remaining above the action level. * 90th percentile value dropped to 12 ppb. Round 3 – 2025 (outsourced testing): *121 properties tested; 7 samples exceeded 15 ppb. *This marked the lowest lead levels since 2018. Risk Edge Note: Failures in protocol compliance during routine water quality monitoring can significantly distort risk assessments and delay protective actions, especially for contaminants like lead, where even small exceedances carry health risks. This case underscores that technical rigour in sample collection is not optional, it is central to credible water quality management. Water utilities must ensure that their personnel or contractors are well trained, that chain-of-custody protocols are followed, and that testing is carried out to regulatory specifications. The cost of protocol deviation can far exceed that of preventive compliance. |
Multiple exceedances of the federal lead action level (15 ppb) recorded across three testing rounds in 2024 and 2025. Resources requirement with city committed to replacing 14,000 lead service lines within 5 years ($300 million estimated cost). Reputational impact from public criticism over testing failures and leadership oversight. Testing costs and interim measures exceeded $240,000. Two staff members reinstated; one later promoted. |
Syracuse News Alert courtesy of Mike McGill |
| 484 | 2025 | Recreational freshwater | Plymouth, Massachusetts, USA | Cyanobacteria / Harmful Algal Blooms (blue green algae) | Authorities in Plymouth issued a public health advisory after cyanobacteria blooms were detected in six local ponds: Clear Pond, Big Sandy Pond, Russell Mill Pond, Billington Sea, Little Herring Pond, and Great Herring Pond. The advisory warns residents and their pets to avoid all contact with these water bodies. The alert will remain active until the blooms are no longer visible for two consecutive weeks. The proliferation of cyanobacteria is linked to warm weather, stagnant water, excessive nutrients, and sunlight. Contributing factors include septic systems, fertiliser use, and stormwater runoff, which introduce nutrients that feed the bacteria. Risk Edge Note: Cyanobacteria blooms can develop rapidly in warm, nutrient-rich and stagnant waters, highlighting the importance of routine monitoring of recreational water bodies during favourable bloom conditions. Public health advisories and temporary waterbody closures are essential measures to reduce exposure risks for people, pets and wildlife when harmful algal blooms are detected. Nutrient inputs from sources such as fertilisers, septic systems and runoff can contribute to cyanobacteria blooms, reinforcing the need for catchment-level management to reduce nutrient loading into ponds and lakes. |
Six ponds in Plymouth identified with significant cyanobacteria blooms as of early August 2025. Public health warnings issued to avoid contact with the water due to potential toxin exposure. |
The Patriot Ledger. Alert courtesy of Adrian Thompson. |
| 490 | 2026 | Sewage Contamination | Potomac River (Clara Barton Parkway / C&O Canal area), Montgomery County, Maryland & Washington, DC, USA | E. coli (bacterium) Staphylococcus aureus (including MRSA)(Bacterium) | On 19 January 2026, a section of the 54-mile Potomac Interceptor (PI) sewer line collapsed along Clara Barton Parkway in Montgomery County, resulting in the overflow of more than 200 million gallons of wastewater into the C&O Canal National Historical Park and the Potomac River. The interceptor normally conveys approximately 60 million gallons of wastewater daily to the Blue Plains Advanced Wastewater Treatment Plant. A bypass system was completed and activated on 24 January 2026 to reroute wastewater around the collapsed section and limit further overflows. DC Water initiated daily E. coli sampling at multiple upstream and downstream locations beginning on 29 January 2026. Sampling results showed extremely elevated E. coli concentrations near the overflow location. At the “Near Drainage Channel @ Overflow” site, results reached 570,000 MPN/100 mL on 29 January and peaked at 730,000 MPN/100 mL on 9 February 2026. Monitoring continued through 22 February 2026, with fluctuating but generally decreasing trends observed over time. Public health guidance noted that swimming is not recommended when E. coli levels exceed 410 MPN/100 mL. Independent sampling conducted by University of Maryland researchers detected E. coli levels more than 10,000 times above EPA recreational water quality standards on 21 January 2026, and more than 2,500 times above standards on 28 January at the overflow site. Staphylococcus aureus and an antibiotic-resistant strain (MRSA) were also detected at the sewage entry point. Although DC Water stated that drinking water was not impacted, as the drinking water system is separate from the wastewater system and the overflow occurred downstream of water intake locations, some commentating on the spill, incorrectly cast doubt on the safety of public water supplies. This led to both DC Water and WSSC Water producing significant advisories on their websites, and other communiques, in an attempt to reassure customers. Risk Edge Note: Major sewage overflows can introduce extremely high concentrations of faecal bacteria and pathogens into surface waters, creating significant public health risks for people who come into contact with contaminated water or surrounding land. Rapid environmental sampling following sewage spills is critical to identify the presence and extent of contamination and to inform public health guidance for affected communities. Ageing or underfunded sewer infrastructure can increase the likelihood of large sewage releases, highlighting the importance of sustained investment, maintenance and rehabilitation of wastewater systems. |
Collapse of a 72-inch diameter sewer pipe. Overflow of more than 200 million gallons of wastewater. E. coli concentrations near the overflow site reaching up to 730,000 MPN/100 mL. Levels significantly exceeding recreational water quality guidance (410 MPN/100 mL threshold). Detection of Staphylococcus aureus and antibiotic-resistant MRSA. |
University of Maryland DC Water WSSC Water Alert courtesy of Adrian Thompson and Dr Veronika Zhiteneva |
| 492 | 2025 | Microbial Contamination | Bethlehem, New Hampshire, USA | Giardia (protozoan) | Health officials in New Hampshire investigated a cluster of illnesses caused by the parasite Giardia that were suspected to be linked to consumption of untreated natural spring water in Bethlehem. Five cases of giardiasis occurring in late August were identified by the New Hampshire Department of Health and Human Services (DHHS). At least four of the individuals reported drinking water from the same roadside spring located on Old Franconia Road in Bethlehem, while investigators were awaiting further information about the natural spring used by the fifth individual. Officials advised anyone who had consumed water from the spring, which flows from a white pipe into a roadside collection bowl, to monitor for symptoms of gastrointestinal illness and seek medical testing if symptoms developed. Symptoms associated with Giardia infection include diarrhoea, stomach cramps, nausea, gas and dehydration. The property owner where the spring is located proactively shut off access to the water while laboratory testing of water samples was undertaken by state authorities. Health officials emphasised that natural springs and other untreated surface water sources are not considered potable and may contain harmful microorganisms even when the water appears clean. Risk Edge Note: Untreated natural water sources such as springs are not considered potable and may contain parasites or harmful bacteria even when the water appears clear and clean. Clusters of gastrointestinal illness may signal a shared environmental exposure and should trigger public health investigations and targeted water testing to identify the contamination source. Restricting access to suspected contamination sources while laboratory testing is conducted is an important precautionary step to reduce further exposure during waterborne illness investigations. Any water source should always have a sound sanitary survey conducted to rule out sources of pollution and/or implement appropriate treatment barriers, before consumption. |
Five confirmed cases of giardiasis reported in New Hampshire in late August. Public health advisory issued recommending monitoring for symptoms and medical testing if illness develops. Access to the spring was shut off while water samples were tested for Giardia and other pathogens. |
The New Hampshire Department of Health and Human Services (DHHS) NBC Boston Alert courtesy of Adrian Thompson. |
| 493 | 2025 | Aesthetic Failure, Treatment Plant Failure | Fort Lauderdale, Florida, USA | Colour, Organic matter | In September 2025, residents in Fort Lauderdale, Florida reported that their tap water appeared discoloured. City officials explained that the temporary colour change was linked to ongoing infrastructure upgrades to the city’s water treatment system and preparation work for a new treatment facility. As part of the upgrade process, crews were flushing raw water piping to remove sand, grit and other debris. This process required drawing water from wells containing naturally higher organic content, which can give water a yellow-brown tint. Officials stated that this colour is associated with organic material originating from vegetation in the Everglades, which naturally affects regional water sources. City representatives emphasised that the water continued to meet all primary drinking water standards, and routine testing was conducted daily to ensure compliance with safety requirements. Authorities also noted that the temporary appearance issues are expected to be resolved once the Prospect Lake Clean Water Center and Prospect Wellfield improvements are completed, with the new facility planned to be operational in fall 2026. Risk Edge Note: Infrastructure upgrades and system flushing can temporarily affect aesthetic water characteristics such as colour, highlighting the importance of proactive communication with consumers during operational changes. Routine monitoring and transparent reporting of water quality results are critical to maintaining public confidence when visible changes occur in drinking water systems. Timely communication with customers ahead of any works, as well as during an event, is essential to inform people about what to expect, duration of events, what to do, and overall, reduce uncertainties. |
Temporary discolouration of tap water reported by residents. Public concern among residents regarding water safety. |
CBS News Alert courtesy of Glenn Barnes |
| 494 | 2023 | Aesthetic Failure | Haizuka Reservoir, Miyoshi City, Hiroshima Prefecture, Japan | Methylisoborneol (MIB), Taste and Odour Compounds | In May 2023, unusually high concentrations of the taste-and-odour compound 2-methylisoborneol (2-MIB) were detected in the Haizuka Reservoir in Miyoshi City, Hiroshima Prefecture, Japan, a reservoir used as a water source. The compound is produced by certain cyanobacteria and actinomycetes and causes a strong musty smell in water. Monitoring revealed that 2-MIB concentrations reached 3600 ng/L in the reservoir, the highest level recorded there since monitoring began in 2015. Following this event, 2-MIB was also detected at the Mukoeda Water Purification Plant, located approximately 5 km downstream of the reservoir, with concentrations ranging between 58 and 120 ng/L in treated water sources. The study investigated the environmental conditions associated with the event and identified cyanobacteria of the genus Pseudanabaena as the primary producer of the compound. The research also examined water quality indicators, meteorological conditions, and biological markers to understand the drivers of the 2-MIB episode. Risk Edge Note: Taste and odour events in drinking water reservoirs can be caused by cyanobacteria and some actinomycetes producing compounds such as 2-methylisoborneol, which may affect drinking water taste and odour even at very low concentrations. Integrated monitoring of cyanobacterial populations, metabolite-producing genes, water quality parameters, and meteorological conditions can help identify drivers of taste-and-odour episodes in source water reservoirs. Reservoir-to-treatment-plant monitoring is important because taste-and-odour compounds produced in source waters can propagate downstream, affect drinking water treatment operations and need additional operational resources to deal with increased customer complaints. |
High concentration of 2-MIB (3600 ng/L) detected in Haizuka Reservoir in May 2023. Taste-and-odour compound detected downstream at Mukoeda Water Purification Plant (58–120 ng/L). Musty odour compounds in raw water created treatment challenges and additional treatment requirements for drinking water supply. |
Hayashi, S. et al. (2025) |
| 496 | 2025 | Microbial Contamination | Maasmechelen, Limburg Province, Belgium | Legionella (bacterium) | In September 2025, health authorities in Maasmechelen, Belgium, reported six cases of Legionella infection within one week. The bacterium can cause a severe form of pneumonia known as Legionnaires’ disease. The Department of Care (Departement Zorg Vlaanderen) began investigating the situation after the first case was reported to local authorities, followed by additional cases during the same week. Local doctors and hospitals in the region were asked to remain alert and to immediately report any new suspected infections. Authorities initiated an investigation to identify the possible environmental source of exposure. Patients were interviewed to determine where and when they may have been exposed in order to help identify potential contamination sources. At the time of reporting, the source of the infections had not yet been identified. Health officials stated that while Legionella occurs naturally in water, a cluster of infections can indicate the presence of a high-risk exposure environment. Authorities emphasised that the overall risk of infection remains relatively low and that most exposed individuals do not become ill. Risk Edge Note: Clusters of Legionella infections can indicate the presence of an environmental exposure source, requiring rapid epidemiological investigation. Early notification to healthcare providers helps improve case detection and reporting during suspected Legionella outbreaks. Legionella infection is of particular concern for those with immune impairment such as older and inform individuals, smokers and infants. |
Six confirmed Legionella infections reported within one week in Maasmechelen. Health authorities launched an investigation to identify the source of exposure. Additional operational resources required to manage the investigation. Local doctors and hospitals asked to remain alert and report new suspected cases. |
VRT NWS Alert courtesy of Adrian Thompson |
| 497 | 2025 | Facility management. Cooling tower management. | Marshall County, Iowa, USA | Legionella (bacterium) | On 4 September 2025, the Iowa Department of Public Health first confirmed a cluster of Legionnaires’ disease cases in Marshall County, initially reporting 18 cases. By 25 September 2025, the Iowa Department of Health and Human Services confirmed an additional case, bringing the total number of confirmed cases in the county to 74 since the outbreak began. All confirmed cases were reported in north-central Marshalltown. Officials suspected the outbreak may have originated from cooling towers in the area. The Marshall County public health director announced plans to test all cooling towers in Marshalltown, and samples were sent to Iowa City for laboratory testing. Officials stated that it could take weeks to receive results. State and county health departments urged businesses and property owners, particularly those operating cooling towers, to review their water management practices. On 4 November 2025, state officials announced that the outbreak had officially ended on 23 October 2025, which was 28 days after the last confirmed case. While it was believed to have originated from cooling towers in north-central Marshalltown, the exact cause of the outbreak remained unknown. Risk Edge Note: Legionella outbreaks can spread through contaminated aerosolised water droplets, particularly from systems such as cooling towers, highlighting the importance of maintaining and monitoring building water systems that can generate mist. Rapid identification and investigation of clusters of Legionnaires’ disease cases are essential to help public health authorities trace potential environmental sources and implement control measures. Water management practices in buildings and facilities, especially those with cooling towers, are critical to preventing Legionella growth and reducing the risk of large community outbreaks. |
74 confirmed Legionnaires’ disease cases. Two confirmed deaths. Cooling towers identified as suspected source; investigation conducted. Exact cause remained undetermined. |
KCCI des moines news KCCI des moines news Alert courtesy of Adrian Thompson and Nick Drust. |
| 498 | 2025 | Treatment Plant Failure, Climate Related Failure | North Somerset (Cheddar Reservoir and Cheddar Water Treatment Works), England, UK | Cyanobacteria, Harmful algal blooms | In September 2025, bottled water was delivered to vulnerable customers in North Somerset, England, as a precautionary response to an operational issue at a water treatment works in Cheddar. The issue was linked to algal blooms in Cheddar Reservoir, which affected the treatment process. Bristol Water announced that Priority Services Register customers (Category 1 and 2) - including individuals with medical conditions, disabilities, or other vulnerabilities - would receive bottled water deliveries. The measure was described as precautionary while the situation at the treatment works was addressed. The company stated that customers would be informed if any impact to water supplies occurred. In response to broader concerns about algal blooms, water companies also reported plans to develop an early warning system combining satellite imagery, drone monitoring, water quality data, and artificial intelligence to detect algal blooms earlier and improve water management. Risk Edge Note: Algal blooms in source water reservoirs can disrupt drinking water treatment processes, requiring precautionary measures to protect vulnerable consumers. Priority services registers help utilities provide targeted support, such as bottled water deliveries, to vulnerable customers during supply incidents. It is essential that these registers are reviewed frequently, to ensure details remain current. Early warning systems combining remote sensing, water quality monitoring, and artificial intelligence may help utilities detect algal blooms earlier and reduce operational risks. |
Precautionary bottled water deliveries provided to vulnerable customers registered under Priority Services. Operational issue at Cheddar water treatment works linked to algal blooms in the reservoir. Water company initiated monitoring and precautionary measures while addressing the treatment issue. Additional costs of supplying bottled water. |
ITV News Alert courtesy of Adrian Thompson. |
| 499 | 2025 | Microbial Contamination, Facility Management Failure (Cooling Towers) | Westchester County, New York, USA | Legionella (bacterium) | In September 2025, health authorities reported 38 cases of Legionnaires’ disease in Westchester County, New York, representing a more than 50% increase compared with the 24 cases recorded the previous year. Two fatalities linked to the disease were reported by county officials, involving residents from New Rochelle and White Plains. Health officials stated that the two deaths were not related to each other. Among the reported cases, five were believed to be part of a cluster in Yonkers. State health authorities began investigating potential environmental sources and identified approximately a dozen cooling towers within a two-mile area in Yonkers, where environmental sampling was initiated. Health officials noted that the increase in cases was consistent with a similar trend reported in New York City, and stated that Legionnaires’ disease is caused by Legionella bacteria that can grow in building water systems such as cooling towers. The Westchester County Health Department reported that it works regularly with building managers to test and disinfect cooling towers and ensure compliance with state and local regulations to reduce the risk of Legionella exposure. Risk Edge Note: Clusters of Legionnaires’ disease cases can trigger targeted environmental investigations of building water systems, particularly cooling towers. Routine testing, disinfection, and regulatory monitoring of cooling towers are key measures used by health authorities to reduce the risk of Legionella exposure. Public health surveillance systems can identify increases in Legionnaires’ disease cases and prompt investigations into potential environmental sources. |
38 confirmed cases of Legionnaires’ disease reported in Westchester County in 2025. Two fatalities reported, involving residents of New Rochelle and White Plains. Five cases identified as part of a cluster in Yonkers. Authorities initiated testing of approximately a dozen cooling towers within a two-mile radius in Yonkers. Building owners are required to test cooling towers every 90 days and report results to authorities. |
Rockland/Westchester Journal News Yonkers Times Alert courtesy of Adrian Thompson. |
| 500 | 2025 | Microbial Contamination | Orléans, Loiret, France | Legionella (bacterium) | In September 2025, traces of Legionella bacteria were detected during testing in the showers of the municipal ice rink in Orléans, France. Following the discovery, a treatment was carried out, but authorities indicated that it would take around ten days for the treatment to become effective. During this period, the ice rink remained open to the public; however, the locker rooms were closed, preventing the organisation of sporting competitions. The closure disrupted the start of the season for the local ice hockey club, the Renards d’Orléans, which had scheduled home matches that now required relocation or adjustment. Risk Edge Note: The incident highlights the importance of routine monitoring and rapid response when Legionella is detected in facility water systems. Temporary closure of high-risk areas such as showers can reduce potential exposure while remediation treatments are implemented. Back-up plans should be in place to ensure business continuity during water quality failures such as a Legionella finding. |
Locker rooms at the Orléans ice rink were closed for at least ten days following the detection of Legionella traces in the shower facilities. Disruption of sporting competitions and scheduled matches for the local ice hockey club. Revenue losses due to the disruption of scheduled home matches. |
Ici (France bleu) Alert courtesy of Adrian Thompson. |
| 501 | 2025 | Recreational Water Failure (Natural Waterways) | Virginia Beach, Virginia, USA | Vibrio vulnificus (bacterium) | In September 2025, a 64-year-old man from Virginia, Derek Michael D’Arcy, died after contracting the flesh-eating bacterium Vibrio vulnificus during a family trip to Virginia Beach. According to his wife, the infection occurred after he waded in calf-deep coastal water while having a cut on his leg. The bacteria entered his bloodstream through the wound and rapidly spread throughout his body. D’Arcy developed necrotising fasciitis and required the amputation of both legs in an attempt to control the infection. Despite medical intervention, he died less than thirteen days after the exposure. Risk Edge Note: Vibrio vulnificus naturally occurs in coastal and brackish waters and can infect individuals through open wounds exposed to contaminated water. Severe infections may progress rapidly and can lead to necrotising fasciitis, amputation, or death. According to the report, the victim had underlying health conditions and had been on home dialysis following previous cancer treatment, which may have increased vulnerability to severe infection. Persons with open wounds should not swim in undisinfected water, particularly warm and brackish waters, due to the risk of infection and disease. |
One fatality linked to Vibrio vulnificus infection after coastal water exposure through an open wound. Emergency bilateral leg amputation performed due to necrotising fasciitis. |
People News Alert courtesy of Adrian Thompson. |