Toilet-to-Tap Project in Tucson, AZ

In a time where water scarcity is becoming an increasingly pressing issue, the potential of recycled water to revolutionize sustainable development cannot be overstated. By integrating advanced wastewater treatment systems into urban planning, cities can address critical environmental challenges and ensure a reliable water supply for future generations. The innovative use of recycled water stands as a beacon of hope, promising a more resilient future for communities worldwide.

Tucson is taking a significant step towards water sustainability by building its first facility to turn recycled wastewater into drinking water. This project, often referred to as “toilet-to-tap,” is funded by the Bureau of Reclamation and aims to reduce the city’s dependence on Colorado River water. 

The initiative is part of a broader vision to create a hydro-local community that values and stewards local water resources. The new facility will treat recycled water to meet EPA drinking water standards, adding diversity to Tucson’s water supplies and addressing increasing PFAS contamination in local groundwater wells. This project is a proactive response to required cuts in Colorado River water allocations, showcasing Tucson’s commitment to water conservation and sustainability. 

Watershed Management Group (WMG) envisions a hydro-local Tucson, where local water resources are prioritized over distant aquifers and rivers. By reusing water multiple times locally, Tucson can extend the use of its limited water supplies and contribute to the health of both local rivers and the Colorado River system. Tucsonans have been reducing their water usage, with the current average at 74 gallons per person per day. WMG aims to further reduce this to 40 gallons per person per day, which could potentially eliminate the need for Colorado River water entirely. Recycled water is already being used to enhance flows in the Santa Cruz River, recharge aquifers, as well as irrigate schools and parks. WMG advocates for prioritizing groundwater recharge and river flow over less critical uses, like golf course irrigation.

Tucson's approach to water recycling exemplifies a forward-thinking commitment to sustainability and resource management. By transforming wastewater back into our most valuable resource, the city is not only addressing immediate water scarcity challenges but also setting a precedent for other communities to follow. The "toilet-to-tap" initiative underscores the importance of local water stewardship and the potential for recycled water to secure a resilient future. As Tucson continues to reduce its water usage and prioritize local resources, it paves the way for a hydro-local model that could revolutionize water management practices nationally.

How to Overcome the "Yuck" Factor of Recycled Wastewater

For those of us who live in places where there is never any doubt about the ability to turn a tap and have clean water come out, it can be hard to reconcile the reality that the world is at great risk of a water supply crisis. In 2023, the UN estimated that not only do two billion people not have safe drinking water, but that two to three billion people are already experiencing water shortages for at least one month a year. The report also projects that the population facing urban water scarcity will double by 2050, due to the increasing frequency of extreme drought.

And drought isn’t the only supply issue — many groundwater aquifers have been overpumped for decades. The Ogallala Aquifer, the largest in North America, supplies 30% of the irrigation water in the United States, is the only reliable source of water in some parts of the American heartland, and will run out of water in a generation in the most vulnerable communities.

So what are we to do about our water supply problems? Yes, we could and should certainly try to use less water, look for other surface water sources, or even pump water back into depleted aquifers.

We could also recycle our wastewater. But, well. That seems “yucky” to a lot of people.  

In Tampa, former Florida state representative and state senator Janet Cruz lost an election in 2023 to the Tampa City Council, largely attributed to her support of laws allowing treated wastewater into drinking water systems while she was a state legislator. In a survey conducted for research published in the Science of The Total Environment journal last year, it was found that just 43% of respondents in the Southeast US supported water reuse generally — and only 8% would be willing to drink recycled water.

But the fact of the matter is that the rest of our water sources cannot be relied upon as we continue to use them in unsustainable ways, and the total volume of our wastewater represents an invaluable opportunity to reshape our water future, if we can just get beyond that “yuck factor.”

To that end, the State Water Resources Control Board of California voted in December 2023 to adopt regulations to implement direct potable reuse (DPR) in the state — in other words, that means treating wastewater to the point that it can be added directly into drinking water systems, with no environmental buffer. The vote was years in the making and the development of the regulations mandated by state law.

California, with its population of 40 million and extremely high demand for agricultural irrigation water, faces the stresses of water supply perhaps more than any other state. The move to implement DPR follows decades of indirect potable and non-potable reuse in the state (and many others in the country, like Florida). Treated wastewater is already being used for industrial machines, irrigation, and aquifer replenishment.

At the time the legislation went through, the Metropolitan Water District alone (the water agency of Southern California) was projected to provide 115 million gallons of recycled water a day by 2032, which could supply 385,000 homes. Gov. Gavin Newsom projected that recycled water could account for 9% of state water use by 2030 and then double by 2040.

The statewide regulations officially allowing for DPR in California went into effect in October of last year. By then, cities like Santa Monica were hoping to implement DPR as early as 2027. Plans for a full DPR treatment facility in the San Fernando Valley to be completed by the same time point are underway. These rules also allow water agencies flexibility in their supply management between wet and dry years, meaning that the objective is that drinking recycled water will help the agencies save water from the Colorado River and Sierra Nevada snowpack for drier years.

But for all the high hopes in California, the state won’t be the first in the nation to treat its wastewater to drinking water quality. The city of Big Spring, Texas, was the first place in the country to use DPR to supply its water system, which it began in 2013 after its namesake spring ran out of water. The standard bearer of water recycling, though, is Singapore, which through its Changi Water Reclamation Plant cleans 237 million gallons of wastewater a day and brands the treated water as “NEWater.”

And California won’t likely be alone as the sole mass consumer of wastewater-turned-drinking-water in the US either. The city of El Paso is expected to have a DPR plant online by 2027, as Texas allows such plants on a case-by-case basis. Colorado actually beat California to adopting DPR regulations in February of 2023, which were the first in the nation. And despite Cruz’s loss in the Tampa City Council election, the practice is still moving forward in Florida, where a pilot program in a central Florida county began turning wastewater to drinking water in late 2023.

Finally, Arizona also began building a framework for DPR late 2023, where the need is increasingly being seen as inevitable. The state’s proposed rules are nearing approval.

Of course, building the needed facilities and the extensive water treatment process won’t come cheaply, especially for municipalities that aren’t quite the size of the whole state of California or even just El Paso. The DPR facility constructed by the Colorado River Municipal Water District for Big Spring, which has a population of around 25,000, cost $14 million to build and took 11 years to plan and construct. Getting other smaller communities on board before it’s absolutely necessary will likely not be easy.

But getting the infrastructure for DPR and other expanded water recycling systems in place now will be cheaper than in the future, when other water sources are even more stressed. And as with all things, as the wastewater recycling economy scales up, costs should come down. It’s already cheaper than desalination of saltwater — an International Finance Corporation estimate has found that the cost of producing potable water can be as low as $0.45 per cubic meter, while desalination typically exceeds $0.50 per cubic meter. A Framework for Direct Potable Reuse put together by water stakeholders including the WateReuse Association and the American Water Works Association also found the total estimated costs of DPR to compare favorably with the costs of other possible new sources of water.

So what does this all tell us about how we get people past that “yuck” factor? We might infer that when faced with nearly no other options, that factor simply goes away. But we don’t have to view recycling wastewater into drinking water as a last resort, either. While the intensive cleaning process isn’t cheap, it results in energy savings, environmental benefits, and water that is purer than many current drinking water sources, as noted by the California State Water Board chair. And who could reasonably argue that those are bad things?

In the end, shifting attitudes beyond the yuck factor may simply require some creativity and a massive PR campaign. Epic Cleantec, a water recycling company in San Francisco, developed a beer from recycled greywater from a city apartment building. Admittedly, greywater — the wastewater from sinks, showers, and laundry — is quite a different thing than the sewage that comes from toilets. But it’s wastewater all the same, and the company has found that people will usually try it. And it’s not the only wastewater beer that’s available, either.

But there’s far more opportunity for wastewater than just beer or even regular drinking water. In their reporting on the subject, Wired magazine posited that “the city of tomorrow will run on your toilet water” — because of the additional possibilities to extract compost and energy. Industries in the EU are already taking steps to get power, heat, and reusable chemical materials out of wastewater.

So as Wired put it, “It’s not gross. It’s science.”

FOR MORE:

• WateReuse Association
  • Recycled Water Users Network
  • National Advocacy Resources
• Framework for Direct Potable Reuse
  • Produced by the WateReuse Association, American Water Works Association, Water Environment Federation, and National Water Research Institute
• As water reuse expands, proponents battle the 'yuck' factor | KFF Health News
• California prepares to transform sewage into pure drinking water under new rules | Los Angeles Times
• Beyond the yuck factor: cities turn to ‘extreme’ water recycling | Yale Environment 360
• The city of tomorrow will run on your toilet water | WIRED
• Recycling sewage is a sensible way to improve water security – but would you swallow it? | The Conversation
• Facility Converting Wastewater into Drinking Water is Coming to the San Fernando Valley | San Fernando Sun
   
• WaterOperator.org Documents Library >> Select ‘CATEGORY’ in the dropdown, and then choose ‘Water Reuse’ to see the resources we have collected on Water Reuse.