Construction is currently underway for a stormwater and wastewater recycling project beneath the Santa Monica City Hall parking lot, as reported by LAist. California is entering a new era with water recycling, a method once labeled by critics as “from toilet to tap.” The state’s new regulations on direct potable reuse now allow treated wastewater—water typically flushed down toilets or drained into sewers—to be processed to drinking standards and directly supplied to homes and businesses.

Mickey Chaudhuri, the water quality management chief at the Metropolitan Water District of Southern California (MWD), emphasized that these regulations provide MWD and other water agencies with greater flexibility in addressing the extreme wet and dry cycles exacerbated by global fossil fuel pollution. “Whether it’s a drought or a wet year, recycled water can enhance our supply sources, improving our resilience to extreme climate events,” he stated.

Southern California has been utilizing recycled water for park and golf course irrigation for decades, with the Orange County Water District leading the globe in promoting safe recycled drinking water methods for over 15 years.

Previously, California law only permitted indirect potable reuse, which involved injecting highly treated wastewater into underground aquifers for further natural filtration before it could enter residential and commercial water systems. The new legislation enables direct reuse, skipping the aquifer step and allowing thoroughly treated wastewater to enter drinking water treatment plants immediately for public distribution.

Climate change is causing prolonged and more severe droughts, straining California’s already limited water supply. By 2040, the state is projected to lose 10% of its traditional supply—an amount greater than the full capacity of California’s largest reservoir, Lake Shasta. Increasing the use of recycled drinking water is one way for Southern California cities to reduce their reliance on water sources from the Colorado River and Sierra Nevada snowpack, which have become less reliable.

However, not every city can store recycled water in underground basins, either due to space constraints or the distance of their existing reservoirs from wastewater treatment facilities, making it financially impractical to recycle more water. The new regulations allow recycled water to enter local treatment systems directly, enabling more cities to recycle drinking water, even without aquifers.

Sunny Wang, the water services manager for Santa Monica, shared that the city is constructing one of the world’s most advanced and unique water recycling facilities, capable of recycling both rainwater and wastewater, located underneath the city hall parking lot. They hope to implement direct wastewater recycling as early as 2027.

Ensuring safety with strict standards is paramount. MWD is currently collaborating with the L.A. County Department of Public Health to build the world’s largest water recycling system. Presently, approximately 250 million gallons of wastewater in the county undergoes treatment that brings it to a clean level but not to drinking standards, before being discharged into the ocean, just a few miles offshore. The aim is to upgrade all wastewater to drinking standards.

The regulations surrounding this water recycling initiative are the strictest in the nation. “People need to overcome their mental barriers about where the water comes from,” Wang explained. Some ask, “Why not utilize more rainwater?” In reality, rainwater runoff can be contaminated with heavy metals, oil, and grease. “We actually need to use wastewater to dilute rainwater to make it easier to treat,” he noted, explaining that wastewater contains primarily organic impurities which are easier to manage.

Chaudhuri indicated that the implementation of this law might lead to increased water fees, although the extent of these increases will depend on each agency’s water system and the high initial costs of necessary infrastructure. MWD’s water recycling facility is expected to reclaim up to 150 million gallons of water daily, with an estimated cost of $6 billion. Santa Monica’s new facility will cost $96 million and is set to recycle about 1 million gallons of water per day.

Chaudhuri highlighted that recycled water is significantly cheaper than desalination, and once the infrastructure is in place, the cost of recycled water will become comparable to imported water. Wang added that once the necessary infrastructure is completed, direct potable reuse will be more cost-effective for many cities.