Treatment and Control of Contaminants Research
- Pathogens
- Contaminants of Emerging Concern (CEC)
- Chemical Contaminants
- Related Research
- Models and Tools
- Publications
Pathogens Research
Opportunistic pathogens, like Legionella, continue to be one of the leading causes of drinking water related disease outbreaks. Other pathogens, including a wide variety of bacteria, protozoans, and viruses, also pose significant human health risks. Current treatments of pathogens include the use of disinfectants, such as chlorine and monochloramine, UV treatment, and filtration. To control and minimize the presence of these organisms, sufficient disinfectant residuals need to be maintained in the drinking water distribution system. In addition, systems need to balance the management of pathogens while minimizing the risk posed by the formation of disinfection byproducts (DBPs).
Small- to medium-sized drinking water systems often have limited resources and expertise to evaluate and install innovative technologies. As a result, they typically do not optimize operations. EPA research aims to help utilities optimize disinfection practices and manage water quality throughout the drinking water system to reduce opportunistic and other pathogens.
EPA is conducting research to develop best practices, tools, and information for assessing and controlling pathogens and biostability in drinking water systems, managing disinfectant residuals, and minimizing DBPs. Research focuses on:
- Understanding the occurrence, prevalence, and control of Legionella throughout the drinking water system and improving treatment technologies and management practices to control this organism.
- Using bench scale and computer-simulated approaches in determining effective disinfectant concentrations to treat pathogens in distribution systems and premise plumbing while minimizing DBP formation.
- Examining the relationships between health risks associated with DBPs, disinfectant residuals, pathogen occurrences and corrosion control of public distribution systems and premise plumbing.
- Measuring exposure and human health effects from pathogens and DBPs found in distribution systems.
Contaminants of Emerging Concern (CEC) Research
Contaminants of emerging concern (CEC) are chemicals that have not previously been detected in water, or that are being detected at significantly different levels than expected. These include a wide array of potential pollutants, such as pharmaceuticals, personal care products, per-and polyfluoroalkyl substances (PFAS), surfactants, microorganisms, microplastics, and endocrine disrupting chemicals, among others. Factors such as shrinking water and financial resources, climate change, agricultural runoff, harmful algal blooms (HABs), and industrial land use increase the probability of CECs found in consumers' drinking water. This issue is likely to disproportionately affect small drinking water systems due to limited resources and treatment options, among other factors.
These unregulated contaminants can also occur in wastewater, reused water, or other matrices and there is often an incomplete understanding of the risk posed by these potential pollutants. Often CECs are difficult to measure and can be linked to many current and historic sources. EPA’s research investigates analytical methods, occurrence, health effects, and treatment assessments to aid regulatory decision making to ensure that these CECs are at safe levels in drinking water as well as wastewater and reused water.
EPA's research on CECs in drinking water focuses on:
- Developing methods and models to estimate and predict contaminant occurrence, toxicity, and risk in drinking water.
- Developing integrated models of multi-route and multi-contaminant exposures to improve assessment methods for detection and quantification of priority CECs in drinking water.
- Filling key knowledge gaps to support and enhance regulatory decisions for chemical and microbial contaminants in drinking water, including the assessment of dermal impacts of chemical contaminants, measurement methods for priority CEC contaminants, and evaluation of point-of-use (POU) filters for contaminant sampling.
- Developing innovative approaches for evaluating exposure to and toxicity from chemical mixtures in drinking water including the use of gene-expression biomarkers to distinguish different mixtures and in vivo toxicity of DBP mixtures to predict proportional response.
Chemical Contaminants Research
Nitrate
EPA is investigating innovative methods for nitrate reduction, including bench-scale experiments on the reduction of nitrate by sulfur, a process that can reduce the need for chemical handling among small drinking water systems. Researchers are also investigating an anaerobic biological denitrification pilot system. Initial research demonstrates that these innovative methods achieve good nitrate removal and have important operational benefits as compared to existing drinking water denitrification systems, such as less frequent backwashing and reduced chemical costs, and show promise for small community applications.
Arsenic
EPA researchers are investigating arsenic accumulation and release from old cast iron water mains into water distribution systems, leading to arsenic levels above allowable limits and threats to consumer health. Research includes surveys of arsenic drinking water throughout the United States, and testing the addition of orthophosphate to drinking water as a method to reduce arsenic release.
Biological Treatment
EPA researchers are investigating biological treatment of drinking water for manganese, ammonia, arsenic, and iron. Research focus includes a pilot-scale biological treatment study for manganese removal, a pilot-scale biological treatment study for ammonia removal, and the biological treatment of arsenic. One of the major potential advantages of biological treatment processes is the minimal need for chemical handling and processes oversight. These advantages in turn make the process potentially advantageous for use in small drinking water treatment systems.
Disinfection Byproducts
EPA is researching effective management of DBPs in distribution and premise plumbing systems while effectively reducing opportunistic premise plumbing pathogens (OPPPs). Researchers use bench scale and computer-simulated approaches to determine effective disinfectant concentrations to treat OPPPs while minimizing DBPs. Additionally, research seeks to understand the relationships between health risks associated with DBPs, disinfectant residuals, pathogen occurrence and corrosion control of distribution systems and premise plumbing. Finally, EPA’s research provides tools for effective disinfectant residuals to control pathogen occurrences while minimizing DBPs in the distribution systems.
Examples of this research include the following:
- Research on disinfectant penetration into biofilm and sediment using microelectrodes to measure disinfectant (free chlorine and monochloramine) concentration gradients within biofilms.
- Development of web-based applications to provide kinetic simulations of inorganic chloramine chemistry as well as the equilibrium chemistry between free chlorine, cyanuric acid, and chlorinated cyanurates. The applications serve as learning tools for drinking water operators, engineers, researchers, and students by providing an interactive environment to explore and understand these water chemistry scenarios.
- Application of bioassays to evaluate the toxicity of DBP mixtures.
- Development of models to help utilities generate effective concentrations of chloramine disinfectant.
Related Research
- Alternative Water Sources
- Drinking Water Treatment and Distribution Systems
- Research on Per- and Polyfluoroalkyl Substances (PFAS)
- Technical Assistance for Water Infrastructure
Models and Tools
- Drinking Water Treatability Database
- Breakpoint Chlorination Simulator for Drinking Water Systems
- Chloramine Formation and Decay Simulator for Drinking Water Systems
- Free Chlorine and Cyanuric Acid Systems Simulator
Research Publications on Contaminants
- EPA Research Publications about Legionella
- EPA Research Publications about Disinfection Byproducts (DBPs)
- EPA Research Publications about Opportunistic Pathogens
- EPA Research Publications about Biological Reduction of Nitrate
- EPA Research Publications about Biological Treatment
- EPA Research Publications about Arsenic in Drinking Water
- EPA Research Publications about Contaminants of Emerging Concern