California’s new toilet to tap water program

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California’s State Water Resources Control Board proposed regulations on Tuesday that would allow for “toilet-to-tap” programs that recycle wastewater and add it back to drinking water systems.

In a statement, the board said: [T]he State Water Resources Control Board announced today proposed regulations that would allow for water systems to add wastewater that has been treated to levels meeting or exceeding all drinking water standards to their potable supplies.

The process, known as direct potable reuse, will enable systems to generate a climate-resilient water source while reducing the amount of wastewater they release to rivers and the ocean. …

Direct potable reuse relies entirely on immediate, multi-barrier treatment that can recycle wastewater to drinking water standards in a matter of hours.

This contrasts to the method currently being deployed in major projects launched throughout the state, called indirect potable reuse, which further improves treated wastewater over time through groundwater recharge or dilution with surface water.

While no formal direct potable reuse projects can be initiated in California until the regulations are adopted, water agencies in Santa Clara, San Diego and the city of Los Angeles have launched pilot projects in recent years.

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a new demonstration project called the Advanced Purification Center, which, when operational, could result in a full-scale recycled water plant that would purify up to 150 million of the 250 million gallons per day that flow through the [Joint Water Pollution Control Plant in Los Angeles, or JWPCP].

The test facility, where construction began in 2017, will be completed later in 2019. It will purify about half a million gallons of water from JWPCP per day, using a special process that first uses microorganisms to remove ammonia and other nitrogen compounds from the water; then uses advanced filters to remove microorganisms and solids; and finally uses [reverse osmosis] membranes to purify the water, just as in a desalination plant.

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