Toilet-to-tap Process Turns Water from “Nasty” to Nourishing
Dow scientists work to find the best methods to make water clean enough to drink

What flows from our membranes is essentially the Rolls-Royce of municipal water.
– Snehal Desai, Global Business Director of Dow Water & Process Solutions

After a day spent basking in the sunshine of Orange County, California, you head inside to pour a cool glass of water from the tap. What you taste is clean, pure and refreshing. You’d never know that just weeks ago that water was … sewage? Really?

You can’t be blamed for thinking this idea far-fetched – or even a little gross. But with Dow technology, it’s not only happening right now through the Orange County Water District (OCWD) Groundwater Replenishment System, it’s also producing some of the most pristine drinking water possible. And as sources of clean water become scarcer, it could be the future of municipal water systems worldwide.

“The purity you get from this process is quantifiably better than the water you get from traditional treatments – better even than some bottled water,” said Snehal Desai, global business director of Dow Water & Process Solutions, in a recent interview with Bloomberg BusinessWeek. “What flows from our membranes is essentially the Rolls-Royce of municipal water.”

Desai is referring to DOW FILMTEC™ Reverse Osmosis (RO) Elements, a system of membranes that purifies water of viruses, pathogens and chemicals. Tiny holes in these membranes are just big enough to allow water molecules to pass through, and small enough to filter out viruses and pharmaceuticals. When combined with a series of other filtering processes – including microfiltration and treatment with UV light, they help produce water that is safe to drink, even from the “yuckiest” of sources.

With 100 million gallons of water purified each day – enough for 850,000 Orange County residents – the OCWD is the largest “toilet-to-tap” system in the world. Dow believes that as the cost of transporting fresh water increases, more locations around the world will begin adopting RO technology to treat sewage, particularly in areas where water is scarce. In fact, the World Water Council projects that recycled sewage will be a normal source of drinking water in cities around the world within 30 years.

“Not every city has an ocean, not everyone has good lakes and rivers,” Desai said. “But everybody’s got sewage.”

DOW FILMTEC™ RO Elements are a key part of Dow’s efforts to use science and technology to address water scarcity worldwide. But these RO elements save energy, too. The OWCD has lowered its energy requirements by 13 percent while producing 30 million more gallons of purified water per day. Taken together, the sustainability benefits of this solution fit squarely into Dow’s 2025 Sustainability Goals and are helping create a “circular economy” that makes the most of existing resources.

This approach is also generating value for Dow from a business standpoint. Dow’s water business has continued to grow as the Company has found innovative new ways to address water challenges and to make its existing RO products more efficient.

“Communities and companies are increasingly realizing the economic value of clean water,” said Andrew Liveris, Dow chairman and chief executive officer. “That’s driving growth in Dow’s water business at two times [the rate of] the global GDP.”

As Dow’s RO technology becomes more widely used, what’s next for the “toilet-to-tap” concept? Desai sees a future where this type of system is made even more accessible – where each flush of your toilet is contributing to your household’s supply of delicious, drinkable water.

“What we’re perfecting at a large scale, for big centralized plants, may become affordable and effective enough to use in a decentralized system, household by household,” he said. “[This way], we each control and regenerate our own water supplies.”

Read the full Bloomberg Businessweek article at their website here.