Study Aims to Set Pathogen Standard for Treated Wastewater

The Water Research Foundation has launched a 24-month project to develop a protocol for measuring pathogens in treated effluent.

Updated on Nov. 3, 2026 in Utilities

Isometric editorial illustration of a clear sampling flask of pale-amber effluent beside a concrete clarifier tank in muted oxblood, teal, and cream tones. — The Water Research Foundation launched a 24-month, 21-utility project led by Carollo Engineers to set a national standard for measuring pathogens in treated wastewater. AI Illustration. Upload story photo >

The Water Research Foundation launched WRF project 5309 to develop a protocol for evaluating pathogen concentrations in secondary effluent. The study is led by Carollo Engineers with 21 utilities across the United States and Australia.

Why it matters

As interest in potable reuse grows, utilities and regulators lack a standardized method for determining pathogen concentrations in treated wastewater. A common protocol could give regulators and utilities a consistent basis for evaluating water quality.

The 24-month project involves 21 utilities and regulatory agencies from Arizona, California, Colorado, Nevada and Utah, with no broadly accepted protocol yet in place for secondary or tertiary effluent. The announcement does not specify the protocol's eventual pathogen targets.

The players

Water Research Foundation

The Water Research Foundation is a nonprofit, educational organization that funds research for the drinking water sector.

Carollo Engineers

Carollo Engineers is an engineering firm with about 1,900 employees in more than 60 offices across North America, founded more than 90 years ago.

Southern Nevada Water Authority

The Southern Nevada Water Authority is the regional water utility serving the Las Vegas area and a co-investigator on the study.

The details

Led by Carollo Engineers, with co-investigators including the Southern Nevada Water Authority, San Diego State University, CDM Smith and Trussell Technologies, the team will review existing regulations and monitoring programs. It will also apply statistical analyses and machine learning to utility pathogen monitoring data.

Over the next 24 months, the research team will develop the pathogen evaluation protocol.

Market Landscape

Interest in potable reuse of treated wastewater is growing across the arid western United States, pushing utilities toward recycling water for drinking supplies. Without a standardized pathogen measurement method, utilities in the region must rely on differing approaches to demonstrate water safety.

Utility customers in water-stressed regions could eventually see treated wastewater used as a drinking supply, depending on how regulators adopt the protocol. The study itself does not change water rates or service today.

The takeaway

A standardized method for measuring pathogens in treated effluent could give utilities and regulators a common basis for judging whether recycled water is safe to reuse. The project's 24-month timeline means any resulting protocol is still well in the future.