From Toilet to Tap

Remember the 1995 movie “Waterworld”? It was set in a future when the raised sea levels covered all continents on Earth after the melting of polar ice caps. At the beginning of the film, Kevin Costner’s character urinated into a plastic cup, ran it through a homemade purifying system consisting of a series of tubes and a pump, and drank the effluent that came out of it. I was so grossed out by that scene that I never watched the rest of the movie. I wasn’t alone. This “yuck” factor has been one of the biggest hurdles for communities that have considered direct potable reuse (DPR) of municipal wastewater (sewage), despite the fact that the technology has long been available to treat wastewater to the level that is safe for drinking. If you feel the same way about DPR as I did before, now is time to do some rethinking.

There was not a drop of rain in Walnut Creek last month. We had some rain in January, but how much more rain and snow we will get this winter in Northern California is anybody’s guess. The water rationing we lived through in the recent past is likely to happen again. Yet we continue to use drinking water for almost everything, including flushing toilets and watering lawns and plants.

In 2016, Central Sanitary District cleaned an average of 32 million gallons of wastewater each day. Only 10 percent of it was recycled. For years in California, the lingering drought and population growth have sent public officials scrambling for more drinking water supply, and tremendous efforts were made at state and local levels in an attempt to make potable reuse of recycled water a reality.

Those efforts culminated in Governor Jerry Brown’s signing of a new law last October that requires the State Water Resources Control Board to adopt, by the end of 2023, uniform water recycling criteria for DPR through “raw water augmentation” – adding treated wastewater into a system of pipelines or aqueducts that deliver raw water to a drinking water treatment plant that provides water to a public water system.

Up till now, the planned use of recycled water to supplement drinking water supplies has been limited to indirect potable reuse (IPR). The difference between direct and indirect potable reuse is that the IPR process includes an environmental buffer and DPR doesn’t. In IPR, highly treated municipal wastewater is injected into groundwater basins or discharged into surface water reservoirs that are used as sources of drinking water. The recycled water remains within these natural bodies for some period of time until pumped out by a drinking water treatment plant. Using recycled water to replenish groundwater basins has been practiced in California for over 50 years, primarily in Southern California.

To date, according to a report published by the State Water Board, there are eight approved projects in the state that use recycled water to replenish groundwater for potable reuse, and more than a dozen projects are being planned by local groundwater management agencies and water utilities. However, using recycled water to augment surface water reservoirs has not been implemented in California because of the public perception factor.

Currently there are only two DPR projects operating worldwide as a permanent source of drinking water. One was in Windhoek, Namibia, which started operation in 1968 during a prolonged drought, and continued as a source of supply after the drought emergency passed. The other project is in Big Spring, Texas. The regional water agency there began to consider using treated wastewater as a new water source during an extended drought cycle that started in the 1990s. Its DPR facility began operating in May 2013, serving several cities including Big Spring, Odessa and Midland. However, no DPR regulations exist today in the United States at the federal or the state level. The projects that were, or are being, approved by the state of Texas have been evaluated on a caseby-case basis.

California’s effort to develop statewide standards for DPR began in 2010 when the Legislature enacted legislation that directed the Department of Public Health to investigate the feasibility of developing uniform water recycling criteria for direct potable use, and to report back to the Legislature by the end of 2016. The responsibility was later transferred to the State Water Board.

The new law signed by the governor last October was the result of that five-year feasibility study. So, 22 years after the film “Waterworld” grossed me out, California has moved one step closer to ensuring that treated municipal wastewater is safe for drinking. And we’re reaching the point that the concept of “toilet to tap” should no longer repel us.

This article first appeared in the January 24, 2018 issue of the Rossmoor News. Author Jennifer Mu can be reached at barnhartmu8833@ gmail.com.

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