A lack of uniform requirements for viral, protozoan, bacterial, and chemical contaminants within reused water obtained from different sources has water reuse program managers having to decide what an acceptable level of risk to human health is for using that water, a federal scientist said during a webcast held by a water-reuse advocacy group. 

The lack of uniform standards for water reuse has been a problem for at least 10 years in part because water reuse is not regulated by the Environmental Protection Agency (EPA), so the agency does not “have water reuse regulations,” said Jay Garland, a senior research scientist at the EPA’s Office of Research and Development. 

That has resulted in regulations being imposed “at the state and local level,” that have created balkanized standards for water reuse, such as with gray water, which is wastewater from household activities like showers, baths, sinks, and washing machines, Garland said. 

However, there have been “good attempts” at determining a standard for “the best level” to approach water quality, such as the NSF/ANSI Standard 350 that has been used throughout the U.S. to certify that systems are operating effectively, according to Garland. However, while the NSF/ANSI Standard 350 “was a great approach for standardization,” later discussions—specifically by the expert panel assembled by the National Blue Ribbon Commission for Onsite Water Systems—determined it “wasn’t risk-based.” 

The lack of an overall risk-based approach has resulted in municipalities and states establishing different water-quality parameters, including for E. coli or fecal coliform that have been “highly variable,” Garland said, adding “you can't have one universal level” for E. coli. 

Furthermore, water-reuse agencies “need to really think about what those risks are, because fecal coliforms are themselves the indicator bacteria, and while they indicate fecal risk, the difference in susceptibility between bacteria and the other microbial pathogens concerned, like viruses and protozoan needs to be addressed, Garland said 

“That’s really the key aspect of, in my mind, the risk-based approach, and why the water quality, the traditional focus on the fecal indicator bacteria wasn’t really capturing what the risk potentially could be for viral for protozoan contamination, he said. 

That has been an issue prompting water reuse mangers to ask “what’s the best level?” for those, Garland said during the webcast that was held on July 17, 2025 by the WateReuse Association, which advocates for laws, policies and funding to increase water reuse. 

Because state or city water agencies establish their own water-quality parameters, the EPA wants to provide those agencies with “the state of science information” to help them determine water-quality parameters, as well as what the acceptable levels of risk to human health are by implementing water-reuse programs, Garland said. 

That requires water-reuse program managers to identify “what the potential risks are” to those who use that water, as well as “what the actual risks are; “what the acceptable risks are,” and “what is my (acceptable) target?” for those risks, he said. 

Therefore, water-reuse agencies have had to decide what is an “acceptable level of risk?” said Garland, who added that while there are different health benchmarks that can be used—including “the degree of the disease, the impact of disease,” and “disability adjusted life years”—one infection per 10,000 people per year is the level that water-reuse agencies seek, and actively treat the water to achieve. 

The WateReuse Association says the webcast featuring Garland is part one of a two-part series with part two scheduled for Sept. 11, 2025 at 10 a.m. during which Michael Jahne, also of EPA’s Office of Research and Development, will speak on risk-based approaches to water reuse. Registration is now open for the second webcast, which is free.