From toilet to tap: Converting wastewater into drinking water

Nov 01, 2024

Engineers say the four-stage filtering process removes viruses, pathogens, bacteria and chemicals.

Engineers say the four-stage filtering process removes viruses, pathogens, bacteria and chemicals.

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Engineers say the four-stage filtering process removes viruses, pathogens, bacteria and chemicals.

Facing a limited supply of drinking water, Westminster officials plan to convert sewage into drinking water.

While some may consider treating wastewater for drinking to be disgusting, it's already a practice in drought-prone areas of the country.

"I think it sounds disgusting. I wouldn't want to drink it," said Sherri Burns, a Carroll County resident.

"That's just a little bizarre, I think, to try to turn sewer water into drinking water," said Cindy Tavares, a Carroll County resident.

While the initial ick factor of turning sewage into drinking water is enough to make some people gag, 11 News Investigates has learned the process of creating the end product will be easy to swallow.

Engineers Ben and Zora Movahed are a Gaithersburg-based couple who designed a system called PUREWater Westminster.

To sell the idea to state regulatory agencies and local officials, the Movaheds built a mini water filtration plant for a nine-month pilot program. They said they collected thousands of samples that often surpassed federal standards.

"I drank it. The director of public works drank it. The mayor drank it," said Ben Movahed, the president of WATEK Engineering Corp.

The process is called indirect potable use, and it begins by diverting filtered, treated wastewater, which would usually be released into the environment, into a new water purification plant. The water is then filtered again through membranes that remove microscopic particles.

"Filtration that takes out viruses, pathogens and bacteria."

"It's a four-stage process: Filtration that takes out viruses, pathogens and bacteria," Ben Movahed told 11 News Investigates. "The membranes are in layers ... The water that passes through the membrane ends us as clean water."

"From there, we take it and further purify it by going through ultrafiltration, reverse osmosis," said Zora Movahed, senior engineer at WATEK Engineering Corp. "The reverse osmosis is the heart of this process."

There are six reverse-osmosis membranes in each of several long white tubes. The process even removes the so-called forever chemicals, per- and polyfluoroalkyl substances.

The water then travels through 6 miles of pipe to the Cranberry Reservoir, which is the primary source of drinking water for Westminster.

WATEK said there are built-in safeguards in case of mechanical issues or power outages. The results led to a change in state law that allows turning sewage into drinking water.

"We are 100% confident that there will not be any issues," Ben Movahed told 11 News Investigates.

"We are 100% confident that there will not be any issues."

Westminster has a long history of water supply struggles, in part because its location is not near a large river or lake. It relies on wells and the Cranberry Reservoir, which are both dependent on rainwater.

"I am definitely a little grossed out about it, but if there is any way to find more sources in water and all that, I think it will be good," said Kathleen Bui, a Carroll County resident.

Construction on the $14 million to $16 million facility in Carroll County begins in January, 11 News Investigates has learned. The plant will treat 10% of Westminster's wastewater and be available to residents in about two years.