U.S. EPA's Water Network Tool for Resilience

Researchers from U.S. EPA and Sandia National Laboratories developed the Water Network Tool for Resilience (WNTR), a "comprehensive scientific software package to help assess a drinking water systems’ resilience to natural disasters. The software improves upon already available capabilities by fully integrating hydraulic and water quality simulation, damage estimates and response actions, and resilience metrics into a single platform. The software is available as an open-source software package and can be applied to a wide range of disruptive incidents and repair strategies." 

Utilities can incorporate WNTR into their existing systems by simulating various scenarios, like power outages or critical pipe breaks, to assess impacts and identify potential repair strategies. WNTR can be utilized in the development of Emergency Response Plans by helping to evaluate and prioritize preparedness strategies and response actions to enhance resilience of the utility. It can also be used to assist in meeting legal requirements, such as those set out in America’s Water Infrastructure Act of 2018, by identifying system vulnerabilities and determining mitigation measures.

The Water Network Tool for Resilience (WNTR) integrates several key features:

• Hydraulic and Water Quality Simulation: WNTR combines hydraulic simulations with water quality analysis to understand how water moves and changes within the distribution system.
• Damage Estimates and Response Actions: It estimates potential damages from disasters, helps utilities to understand how infrastructure damage might occur over time, and evaluates the effectiveness of response actions.
• Resilience Metrics: The tool includes metrics to assess the resilience of water systems under various scenarios.
• Compatibility with EPANET: WNTR is compatible with EPANET, a widely used software for modeling water distribution systems, enhancing its utility and accuracy.

Access the WNTR tool and relevant webinar recordings on U.S. EPA's website.

Water Treatment Resources for Water Operators

Water treatment is the umbrella term for the processes used to make water more acceptable for a desired end-use, including meeting regulatory requirements. Drinking water treatment includes but is not limited to: chemical disinfection, coagulation, sedimentation, filtration, ultraviolet, ozone, membranes, and reverse osmosis. 

We have 1,772 resources (and counting) on Water Treatment in our Documents Database that provide valuable information on this topic. You can search for documents like a guidance manual for alternative disinfectants and oxidants, chlorination controls for small water systems, factsheets on bacteria in drinking water, and many other useful guides that will help you to deliver safe and clean water to utility customers. 

To access the wealth of knowledge on Water Treatment within our database just select "CATEGORY" in the dropdown then choose "Water Treatment." Once you make that selection, a second dropdown will appear where you can choose "HOST," “TYPE,” or “STATE” to narrow the search even further. If you have a specific search term in mind, use the “Keyword Filter” search bar on the right side of the screen.

This is part of our A-Z for Operators series.

Coliform Sampling

There are a variety of bacteria, parasites, and viruses which can cause health problems when humans ingest them in drinking water. Testing water for each of these germs would be difficult and expensive. Instead, water quality and public health workers measure for the presence of bacteria in drinking water using coliform bacteria as an indicator. The presence of any coliforms in drinking water suggests that there may be disease-causing agents in the water.

We have 499 resources (and counting) on Total Coliform in our Documents Database that provide valuable information on this topic. You can search for documents on potential pathways for coliform contamination, coliform bacteria and well water sampling, best practices for coliform sampling, and many other useful guides that will help you to deliver safe and clean water to utility customers. 

To access the wealth of knowledge on Total Coliform within our database just select "CATEGORY" in the dropdown then choose "Total Coliform." Once you make that selection, a second dropdown will appear where you can choose "HOST," “TYPE,” or “STATE” to narrow the search even further. If you have a specific search term in mind, use the “Keyword Filter” search bar on the right side of the screen.

This is part of our A-Z for Operators series.

Radioactive Contaminants in Water

Most water sources have very low levels of radioactive contaminants, most of which are naturally occurring, although contamination from human-made nuclear materials can also occur. Most radionuclides are at levels that are low enough to not be considered a public health concern. At higher levels, long-term exposure to radionuclides in drinking water may cause cancer. In addition, exposure to uranium in drinking water may cause toxic effects to the kidneys. Radiation found in sewage sludge and the ash from its incineration may be from Nuclear Regulatory Commission licensees, industrial discharges, and TENORM.

We have 100 resources (and counting) on Radionuclides in our Documents Database that provide valuable information on this topic. You can search for documents on the management of radioactive residuals from drinking water treatment, approved analytical methods for monitoring radionuclides, uranium as a drinking water contaminant, federal regulations on the disposal of residuals containing radionuclides, and many other useful guides that will help you to deliver safe and clean water to utility customers. 

To access the wealth of knowledge on Radionuclides within our database just select "CATEGORY" in the dropdown then choose "Radionuclides." Once you make that selection, a second dropdown will appear where you can choose "HOST," “TYPE,” or “STATE” to narrow the search even further. If you have a specific search term in mind, use the “Keyword Filter” search bar on the right side of the screen.

This is part of our A-Z for Operators series.

Disinfection By-Product Control

Disinfection kills or inactivates disease-causing organisms in a water supply. Disinfection by-products (DBPs) are formed when disinfectants used in water treatment plants react with bromide and/or natural organic matter, like decaying vegetation, present in the source water to create harmful compounds. Different disinfectants produce different types or amounts of disinfection byproducts.

We have 829 resources (and counting) on Disinfection and Disinfection By-Products in our Documents Database that provide valuable information on this topic. You can search for documents that explain how to use the Drinking Water State Revolving Fund (DWSRF) to address DBPs in drinking water, the basics of ultraviolet disinfection, disinfectant residual control within the distribution system, webinar recordings on ways to simulate disinfectant water chemistry and ways to assess distribution system influent water quality, and many other useful guides that will help you to deliver safe and clean water to utility customers. 

To access the wealth of knowledge on Disinfection and its potential by-products within our database just select "CATEGORY" in the dropdown then choose "Disinfection and Disinfection By-Products." Once you make that selection, a second dropdown will appear where you can choose "HOST," “TYPE,” or “STATE” to narrow the search even further. If you have a specific search term in mind, use the “Keyword Filter” search bar on the right side of the screen.

This is part of our A-Z for Operators series.

Learning Lessons from Supply Chain Disruption

One of the most prominent economic impacts to emerge from the COVID-19 pandemic was the breakdown of supply chains for many consumer, medical, and industrial products. Though the shortages of goods such as toilet paper, semiconductor chips, personal protective equipment and more made widespread headlines, the range of items affected spread much wider — including to the supply of critical water treatment chemicals. The American Water Works Association found in November 2021 that 45% of surveyed water utilities were experiencing shortages of water treatment chemicals, among other staffing and supply issues. 

Shortages of chlorine did make news in the summers of 2021 and 2022 due to the difficulty pool-owners had obtaining it to clean their pool water, but the threat it posed to water utilities — where chlorine is a critical component of the treatment and disinfection process — was much less widely known. In 2021, the pandemic spurred the shortage by causing a decrease in production capacity, an increase in demand (largely from a boom of newly-installed pools), and other logistical failures. However, non-COVID factors also played a role in the shortages.

Hurricane Laura, which struck Louisiana in August 2020, severely damaged the BioLab Inc. chemical plant, a major US producer of chlorine. In 2022, the labor dispute between rail workers and rail companies briefly led to an embargo on the rail transport of hazardous materials including chlorine and other water treatment chemicals. While further major disruptions did not occur in 2023, the EPA considers the chlorine supply chain to be “vulnerable to periods of reduced product allocation and/or price increases” and maintains a page tracking the status of chlorine availability and pricing. 

The most severe supply chain disruption in 2023 for water treatment chemicals came right at the start of the year — when a four-alarm fire devastated the Carus Chemical factory in LaSalle, Illinois, on January 11. Carus is the only producer of potassium permanganate in North America, which is used to oxidize contaminants in drinking water. While the company initially warned of  a 3-month outage in its production capacity, potassium permanganate production did not resume at Carus until August. Luckily, overseas imports were able to fill demand after some initial shortages, and the EPA found that supply had stabilized by May.

Other water treatment chemical supply chains that the EPA considered to be disrupted since 2020 include carbon dioxide, sodium hydroxide and hypochlorite, hydrochloric acid, ferric and ferrous chloride, oxygen, and fluorosilicic acid. However, none of these disruptions are considered to be ongoing.

While supply chains of water treatment chemicals have always been susceptible to periods of economic strain, such as the Great Recession of 2007-09, COVID-19 revealed many more risks in the system. According to the EPA’s “Understanding Water Treatment Chemical Supply Chains” report:  

“The supply disruptions that have occurred during the pandemic era revealed a range and intensity of supply chains stressors that had not previously been observed in such a short timeframe. While high-impact events such as a pandemic or repeated extreme weather events concentrated on industrial hubs may have been considered low-probability in previous assessments, supply chain risk planning may have to consider greater frequency and co-occurrence of such high-impact events.”

The most prevalent long-standing threats to the stability of supply chains include natural disasters, equipment failures, logistical problems such as transportation delays, and malicious acts like cyberattacks and sabotage — none of which will stop being a concern even as the pandemic is increasingly behind us. International markets can also be severely affected by trade barriers, armed conflicts, and natural disasters. 

Perhaps the most prominent chemical shortage preceding 2020 was a national shortage of chlorine in 1974. While a single cause of the shortage could not be identified, New York Times reporting at the time cited the new requirement to chlorinate wastewater, the closure of production facilities, and the energy crisis of the 1970s (which was peaking with the 1973-74 oil shock) as likely factors.

For more information on the supply chain history of various water treatment chemicals, the EPA’s supply chain profiles of 46 commonly used chemicals contains shortage histories for 2000-2022, as well as risk profiles for shortages of each chemical. Risk ratings for these chemicals can also be found in the “Understanding Water Treatment Chemical Supply Chains” report.

As for future concerns, chlorine availability could continue to be made vulnerable by natural disasters in the Gulf Coast region. 33% of American chlor-alkali facilities, in which most chlorine is produced, are located along the Gulf Coast, which is both historically prone to hurricanes and under greater threat as climate change intensifies storms. Disruptions in chlorine supply also lead to disruptions in ferric chloride supply, which requires hydrochloric acid. 

The EPA has many resources to assist in preparing for and responding to supply chain challenges. The critical steps to prepare are:

1. Using federal and state support programs for operational efficiency and cost reduction
2. Management of supplier relationships
3. Coordinating with other utilities, state and local agencies, and water sector associations
4. Instituting operational flexibilities 

To respond to disruptions, the EPA recommends:

1. Seeking federal support
2. Communicating with suppliers
3. Coordinating with partners

Follow the Supply Chain Resilience Guide for more information, instructions, and tips to prepare and respond.  

More information, tools, and links from the EPA: 

• Current Supply Chain Disruptions
• Platform for Coordinating Supply Chain Efforts
• Chemical Suppliers and Manufacturers Locator Tool
• Supply Chain Case Studies
• Water Treatment Chemical Supply Chain Profiles
• Understanding Water Treatment Chemical Supply Chains and the Risk of Disruptions
• Supply Chain Resilience Guide for Water and Wastewater Utilities
   

Arsenic in Drinking Water

Arsenic is a heavy metal and a regulated contaminant in drinking water and wastewater effluent. In 2001, under the Arsenic Rule, EPA adopted a lower standard for arsenic in drinking water of 10 parts per billion (ppb) which replaced the previous maximum contaminant level (MCL) of 50 ppb. Arsenic is a semi-metal element in the periodic table. It is odorless and tasteless. It can enter drinking water supplies from natural deposits in the earth or from agricultural and industrial practices. 

We have 180 resources (and counting) on Arsenic in our Documents Database that provide valuable information on this topic. You can search for documents about the arsenic rule, complying with the arsenic maximum contaminant level, the reporting requirements for the annual Consumer Confidence Reports (CCR), and many other useful guides that will help you to deliver safe and clean water to utility customers. 

To access the wealth of Arsenic related knowledge within our database just select "CATEGORY" in the dropdown then choose "Arsenic." Once you make that selection, a second dropdown will appear where you can choose "HOST," “TYPE,” or “STATE” to narrow the search even further. If you have a specific search term in mind, use the “Keyword Filter” search bar on the right side of the screen.

This is part of our A-Z for Operators series.

PFAS Treatment: What We Know in 2023

PFAS (formally known as per- and polyfluoroalkyl substances) are widely used, long lasting chemicals that break down very slowly over time. They break down so slowly that they end up in water, air, fish, and soil all over the world, and trace amounts have even been detected in human blood. Scientific studies have shown that exposure to some PFAS in the environment may be linked to harmful health effects in humans and animals, but we do not know to what extent they may affect us.

PFAS possess chemical properties that mean traditional drinking water treatment technologies are not able to remove them. Researchers have been working on a variety of treatment technologies to determine which methods work best to remove PFAS from drinking water. Some of the most successful methods include: activated carbon adsorption, ion exchange resins, and high-pressure membranes. 

Granular activated carbon (GAC) adsorption: GAC has been shown to effectively remove PFAS from drinking water when it is used in a flow through filter mode after particulates have already been removed. According to EPA researcher Thomas Speth, this method can be extremely effective “depending on the type of carbon used, the depth of the bed of carbon, flow rate of the water, the specific PFAS you need to remove, temperature, and the degree and type of organic matter as well as other contaminants, or constituents, in the water.”

Ion exchange resins: Negatively charged ions of PFAS are attracted to positively charged anion resins. Anion exchange resins (AER) have proved to have a high capacity for many PFAS; but this method can be more expensive than GAC. The most promising version of this method is an AER in a single use mode, followed by incineration of the resin. This technology has no contaminant waste stream to treat or dispose due to the lack of need for resin regeneration.

High-pressure membranes: Research shows that membranes, such as nanofiltration or reverse osmosis, are typically more than 90 percent effective at removing a wide range of PFAS. However, these methods generate a large volume of high-strength waste stream which can be difficult to treat or dispose of for a water system. This technology may be better suited for a homeowner since it would generate a much smaller volume of waste.

PFAS Resources:

• Drinking Water Treatability Database
  • The Drinking Water Treatability Database (TDB) can be used to identify effective drinking water treatment processes, to plan for future treatment plant upgrades, to provide information to first responders for spills/ emergencies, and to recognize research needs.
• PFAS Analytic Tools hub
  • This page contains location-specific information related to PFAS manufacture, release, and occurrence in the environment as well as facilities potentially handling PFAS.
• CWA Analytical Methods for Per- and Polyfluorinated Alkyl Substances (PFAS)
  • This page contains information regarding the EPA’s development of new analytical methods to test for PFAS compounds in wastewater, as well as other environmental media.

Are Solar Powered Water Treatment Plants the Future?

Clean water and clean energy are both essential on the road to a more sustainable future. To be able to tackle two issues at once and provide clean water using clean energy is exactly the kind of innovation that the world needs. A few wastewater treatment plants across the country are taking matters into their own hands and converting their plants to solar-powered energy. 

The solar farm for the Wastewater Treatment Plant in New Stanton was just finished. The Federalsburg Wastewater Treatment Plant just received over one million dollars in grant funding for the construction of a solar panel system. The city of Danbury, Connecticut is also considering a solar installation that would power their city’s wastewater treatment plant. The Diablo Water District also installed a solar power system in their facility to help them achieve their ambitious goal of being carbon neutral by 2027.

Powering water treatment plants with solar power helps the environment and it can help facilities save money because it can lock in electrical rates. It also makes facilities more resilient to power outages from natural disasters or other power grid failures. Utilities that convert their water treatment facility to solar power help their community and country work towards achieving the renewable energy goals the world is striving towards. 

Featured Video: Disinfection Byproducts in Tap Water: 5 Things To Know

The challenge of disinfection byproduct (DBP) control in drinking water lies in balancing the varying health risks of over 600 known DBPs with the benefits of microbial waterborne illnesses prevented via disinfection. While DBPs can originate from industrial sources, they generally form in water treatment systems when natural organic matter reacts with a disinfectant, usually chlorine-based. Ongoing studies have suggested that the toxicity for any given DBP can range from having no known health effects to exhibiting links between exposure and cancer, birth defects, or reproductive disorders. Disinfectant type and dose, residual chlorine, inorganic and organic precursor concentrations, pH, temperature, and water age can impact DBP formation.

The management of DBPs in drinking water is enforced through the Stage 1 and Stage 2 Disinfection Byproduct Rule (DBPR). Collectively, the rules set maximum contaminant levels (MCLs) for total trihalomethanes (TTHM), 5 haloacetic acids (HAA5), bromate, chlorite, chlorine/chloramines, chlorine dioxide, and DBP precursors.

According to a 2019 report by the U.S. Environmental Protection Agency (EPA), the Stage 2 DBPR invoked the largest number of community water system violations between 2017 and 2018, accounting for approximately 30% of all drinking water violations. Consecutive water systems, those with surface water sources, and systems serving populations of 501 to 10,000 people experienced violations more frequently. A greater compliance challenge is experienced by consecutive systems because they have little control over the water that they receive. While treated water may have achieved compliance at the system’s interconnection, DBP concentrations can rise through the receiving distribution system.

Non-consecutive utilities experiencing compliance challenges for the Stage 1 or 2 DBPR can start by troubleshooting the system using our previous blog post on The Disinfection By-Product Challenge. Consecutive systems should coordinate with their wholesale system following the approaches suggested in the 2019 report discussed above. The preferable methods of control often lie in prevention and optimization. As your system troubleshoots the cause of high DBP concentrations, keep the community informed on your efforts as well as some basic information on the health effects and sources of DBPs. Operators can find a general overview on DBP challenges in this week’s featured video. We recommend using this video to provide customers with answers to the following questions:

• What are disinfection byproducts?
• How are DBPs regulated?
• How do I know if my water has high levels of DBPs?
• How are people exposed to DBPs?
• How do I remove DBPs from my home’s water?