Toilet-to-tap water: Making the case for recycled water with data

Posted: November 15, 2024

Recycled water has a PR problem—one best exemplified in a multi-million-dollar project that met an untimely end in Los Angeles, California.

In 1995, the City of Los Angeles spent $55 million on its East Valley Water Recycling Project, an indirect potable use program. Treated wastewater from a plant in Van Nuys, CA was pumped to “spreading fields” in the San Fernando Valley where—over the course of five years—it would filter through the sandy soil and gravel into the aquifer.^[1]

Five years later, in 2000, when water from the East Valley Water Recycling Project was ready for public use, the reclaimed water project became a topic of debate during LA’s mayoral election. Mayoral candidate Joel Wachs was quoted in the LA Times as saying, “Go tell somebody in North Hollywood that they have to drink toilet water but the mayor [Richard Riordan] won’t have to drink it in [his] Brentwood [home].”^[2] A memorable, though misleading, statement since the aquifer water would be used throughout the city.

In the lead up to the race, “toilet-to-tap” water was a frequent headline in local and state news coverage, and candidate Wachs’s opposition to the project spurred public wariness of reclaimed water. Tonight Show host Jay Leno did a bit on the water reuse project with the sound of a flushing toilet in the background.^[3]

The East Valley Water Recycling Project was quietly shut down after only a few days of use. City Attorney James Hahn put a temporary hold on the project in 2000 and officially shuttered it once he became mayor in 2001.^[4]

The idea of “drinking toilet water” was so off-putting to the public that politicians shuttered a project they’d previously greenlit due to public backlash.

California plans to recycle wastewater into drinking water

Twenty years later, reclaimed water has a second life in LA County. In 2023, California passed legislation that will make it the second state to recycle wastewater into drinking water, but this time, the state intends to invest in direct potable reuse (DPR)—treating grey and brown water at advanced water treatment plants until it is potable.^[5] As a part of LA’s Green New Deal passed in 2019, the city plans to source 80% of water locally by 2045, and as a part of that goal, recycle 100% of the wastewater from the city’s largest wastewater treatment plant by 2035. City leaders believe this plan is crucial to mitigate climate change risk as droughts dwindle freshwater reserves^{.[6], [7]}

Many industry experts believe direct potable reuse is the future of water and wastewater management. Though much of the public isn’t aware of this fact; most already drink some recycled wastewater. Many wastewater treatment plants treat wastewater to rigorous standards and then release the treated water into river systems upstream of water treatment plants, where water is again treated to mandated potable water standards. Direct potable use removes the step of an environmental barrier, such as a river or aquifer, that acts as a buffer between treated wastewater and the potable water supply.

In addition to reducing the strain on local freshwater resources, DPR also saves an enormous amount of water that would otherwise be discarded or pumped elsewhere for non-potable use, such as in agriculture. By reducing the distance water needs to be pumped for further treatment or non-potable use, DPR is also associated with significant energy savings. The United Nations' 2017 World Water Development Report calls recycled wastewater “an untapped resource”—for its potential in addressing water scarcity, reducing pollution from untreated wastewater that ends up in the environment, and for the nutrients, like phosphorus and nitrates, that can be extracted from it for fertilizers^.[8] In light of this, a UNESCO blog asks, “Is wastewater the new black gold?”

Which countries are leading the way in direct potable reuse?

DPR may be novel in the United States, but in Namibia, it has been a mainstay for decades.

In the city of Windhoek, Namibia, DPR dates back to 1968, making it the first city in the world to implement recycled water. The New Goreangab Water Reclamation Plant, built in 2002, remains the largest and most advanced DPR plant in the world; with the assistance of partner companies Veolia and VA Tech Wabag, the plant supplies 25% of drinking water to the city’s 400,000 residents.^[9]

The DPR process at the New Goreangab Water Reclamation Plant

Here’s a look at the multistep treatment process at the plant: First, pre-treatment removes large solids and settles suspended particles. Microorganisms are then used in a biological treatment step/phase to degrade organic matter. Secondary treatment removes finer suspended solids and additional organic compounds. Next, the water is treated with advanced filtration systems using membrane filtration to remove microscopic pathogens, ozonation to disinfect the water by inactivating pathogens, and carbon filtration to remove dissolved organic compounds and other trace contaminants. Finally, the water is chemically treated to adjust its pH and mineral content.^[10]

Bipartisan Infrastructure Law funding brings DPR to El Paso, Texas

For 35 years, El Paso has treated wastewater to drinking water standards and then sent it to the Hueco-Mesilla Bolsons Aquifer, which supplies fresh water for El Paso and Ciudad Juarez. Now, with $20 million in funding from the Bipartisan Infrastructure Law, El Paso Water is building a new DPR wastewater treatment plant to bring recycled water to El Pasoans by 2027.^{[11], [12]} The planned multi-step treatment process includes membrane filtration, reverse osmosis, ultraviolet disinfection with advanced oxidation and granular activated carbon filtration.

“It’s a drought-proof supply,” said John Balliew, CEO and President at El Paso Water. “For every gallon of this water that we produce, it’s a gallon less of river water or well water that we must produce.”^[13]

Building consumer confidence in water quality with data

As the fate of the East Valley Water Recycling Project demonstrates, public opinion of reclaimed water can play an outsized role in the success of water recycling projects. Most municipalities publish semi-regular public reports on water quality, but advocates for recycled water, such as the Natural Resources Defense Council, argue that making near-real-time water quality data available to consumers can assuage consumers’ fears about water quality.^[14] In particular, sharing data about contaminants of emerging concern from pharmaceuticals and personal care products as well as possible pathogen indicators would be the gold standard. Transparent access to data demonstrating consistent water quality would be a dependable means of building the consumer confidence necessary for widespread DPR adoption in municipalities worldwide.

Embracing reclaimed water will not only safeguard water supplies, it will also help communities embody the principles of a circular economy: turning waste into a valuable resource and minimizing environmental impact.

Learn how companies are using AVEVA software to improve water quality.

References:

^{[1] Haefele, M., & Sklar, A. (2007, August 26). Revisiting ‘toilet to tap.’ Los Angeles Times. https://www.latimes.com/opinion/la-op-haefele26aug26-story.html
[2] Ibid.
[3] California Water Environment Association. (2023, October 3). What’s the origin of ‘toilet-to-tap’? CWEA News. https://www.cwea.org/news/whats-the-origin-of-toilet-to-tap/
[4] Ibid.
[5] Hubler, S. (2023, December 19). California allows wastewater to be recycled into drinking water. The New York Times. https://www.nytimes.com/2023/12/19/us/california-wastewater-drinking-water.html
[6] Gold, M. (2020, February 4). Now is the time to go all in on California water reuse. Natural Resources Defense Council. https://www.nrdc.org/bio/mark-gold/now-time-go-all-california-water-reuse
[7] Los Angeles Sanitation & Environment. (n.d.). Pure Water Los Angeles. Retrieved November 7, 2024, from https://sanitation.lacity.gov/san/faces/home/portal/s-lsh-wwd/s-lsh-wwd-cw/s-lsh-wwd-cw-rw/s-lsh-wwd-cw-rw-pwla
[8] United Nations Educational, Scientific and Cultural Organization. (2017). Wastewater: The untapped resource (World Water Development Report 2017). UNESCO. https://www.unesco.org/en/wwap/wwdr/2017
[9] Veolia. (2023). Windhoek municipal water reuse: From wastewater to potable water. Veolia Bulgaria. Retrieved from https://www.veolia.bg/sites/g/files/dvc2926/files/document/2023/09/CSC%20Windhoek%20Municipal%20Namibia%20Water%20EN.pdf
[10] Windhoek Goreangab Operating Company. (2013). Direct potable reuse in Windhoek: New Goreangab Water Reclamation Plant. Asersa. Retrieved from https://www.asersagua.es/Asersa/Documentos/WINGOC%20BIG%20BROCHURE%202013.pdf
[11] Texas Standard. (n.d.). How El Paso’s water system could offer a model for a drier Texas. Retrieved November 7, 2024, from https://www.texasstandard.org/stories/el-paso-water-system-texas-supply-treatment-climate-change/#:~:text=that%20is%20anticipated%20to%20be%20online%20by%202027
[12] El Paso Water. (2023, October 2). New facility funds help lead the way in reuse. El Paso Water. https://www.epwater.org/about_us/newsroom/news_from_the_pipeline/new_facility_funds_help_lead_way_in_reuse
[13] Ibid.
[14] Gold, M. (2020, February 4). Now is the time to go all in on California water reuse. Natural Resources Defense Council. https://www.nrdc.org/bio/mark-gold/now-time-go-all-california-water-reuse}