California turns tide with waste-to-drinking water approach

State approves regulations that allow water agencies to recycle wastewater into safe drinking water; looks to bolster California’s water resilience

(Samopauser on AdobeStock)
Darren Fraser
Published December 26, 2023  • 
12:00 pm

SACRAMENTO – There was a time when the idea of drinking recycled toilet water would make people swoon or feel sick; but now, in a groundbreaking move aimed at addressing climate-driven challenges, the state’s water resources control board has approved innovative regulations allowing water agencies to make wastewater completely safe to drink.

The regulations were approved on Dec. 19 by the California State Water Resources Control Board (SWRCB), which will allow water agencies to develop treatment procedures to capture wastewater, treat it and render it into safe drinking water.

“This is an exciting development into the state’s ongoing efforts to find innovative solutions to the challenges of extreme weather driving by climate change,” State Water Board chair Joaquin Esquivel said via the news release of this announcement.

Esquivel added, “These regulations ensure that the water produced is not only safe, but purer than many drinking water sources we now rely on.”

The state’s goal is to recycle and reuse 800,000 acre-feet of water per year by 2030. According to the state’s water plan, “California’s Water Supply Strategy: Adapting to a Hotter, Drier Future,” state leaders have earmarked over $8 billion to modernize the state’s water infrastructure and management.

The state’s 2022-2023 budget set aside $2.8 billion for drought relief to hard-hit communities, water conservation and for projects to permanently strengthen drought resilience.

As for the SWRCB, the control board has distributed over $1.2 billion to 15 recycling projects across the state. The projects will produce 75,000 acre-feet of water per year by 2030 – enough to sustain 500,000 people annually.

According to the press release, the new regulations mean California now has the most advanced standards in the country for treating and converting wastewater into drinking water. The process – direct potable reuse – enables water systems to create a climate-resilient water source. 

The benefit is twofold for consumers. Direct potable reuse reduces the amount of wastewater discharged to rivers and oceans while adding millions of gallons of drinking water to local water systems.


Drought is a recurring feature in California. The California Department of Water Sources notes the state experienced a five-year drought from 2012 to 2016. Other droughts occurred in 2007 to 2009, 1987 to 1992, and 1976 to 1977 and sporadically over the past two centuries. The past three years were some of the driest years in the state’s history.

Extreme heat affects how the ground absorbs rainwater. Increased temperatures evaporate more water, which means more water stays in the air. The parched earth consumes what’s left.

This cycle has dire implications for the water supply. According to the water plan, if hotter and drier weather remains a constant in the state, it could diminish the state’s existing water supply by up to 10% by 2040.


Darrin Polhemus, SWRCB deputy director of drinking water, told the Associated Press (AP) that wastewater will be treated for pathogens and viruses, regardless of if the pathogens and viruses are not present in the water. Existing treatment procedures only require that water is treated for known pathogens.

Polhemus added that building the treatment facilities takes time and is expensive. For now, these treatment centers may be the province only for larger, well-funded cities.

Orange County Water District has such a system. According to the District’s website, its Groundwater Replenishment System (GWRS), which was completed last April, is the world’s largest purification system for indirect potable use. The system takes treated wastewater that would normally be discharged into the ocean and purifies it using a three-step process that involves microfiltration, reverse osmosis and ultraviolet light with hydrogen peroxide.

GWRS processes 130 million gallons of water per day. The system serves one million people and recycles 100% of reclaimed wastewater flows, meeting 35% of the district’s water demands. SWRCB provided $491 million in funding for the system.

Water agencies in Santa Clara, San Diego, and Los Angeles have rolled out pilot programs in recent years. 

Esquivel told AP that most people in the state drink recycled water now. Wastewater treatment plants discharge treated water back to rivers and streams, and the water flows to the next city.

“Anyone out there taking drinking water downstream from a wastewater treatment plant discharge is already drinking toilet to tap,” Esquivel said. “All water is recycled.”

Darren Fraser