Denver Water wants expand its recycled water program, but health regulators are not sure the proposal is safe.
“Denver Water is asking for state permission to expand the uses of recycled water — to include flushing toilets in commercial buildings, washing cows and pigs at the National Western Stock Show, and irrigating crops such as marijuana,” The Denver Post reported.
“This could increase the 80 or so big customers in metro Denver who already tap a 70-mile network of underground purple pipes carrying recycled water, cleaned to meet the drinking water standards that applied in the 1980s,” the report said.
The utility wants to double the amount of recycled water it supplies. It currently serves up to 2.6 billion gallons of recycled water per year. It wants to offer more than 5.6 billion gallons by 2020, the report said. The utility spells out the benefits of recycled water on its website.
But the Colorado Department of Public Health and Environment has concerns about the plan, according to the newspaper report:
State water quality staffers are reviewing “adequate control of pathogens,” including the potential for bacteria to grow in the purple pipes, an agency spokeswoman said. That’s because irrigation of crops for human consumption could mean more people are exposed to bacteria. They’re also evaluating the potential for salts to build up in soils and groundwater. And they’re looking at issues around build-up of “antibiotic resistant genes” that recycled water could accelerate. (Bacteria that develop resistance to antibiotics can reproduce and pass on that resistance, creating many more antibiotic resistant bacteria.)
It’s not the first time Denver Water’s ambitious water recycling goals have come under scrutiny. For instance, the Denver Zoo “decided to stop feeding recycled water to elephants, rhinos and tapirs in its ‘crown jewel’ exhibit, the Toyota Elephant Passage,” Westword reported in 2015.
The zoo discontinued the program “because the U.S. Department of Agriculture doesn’t have standards beyond recommending potable water,” The Denver Post reported.
To read more about the pros and cons of water recycling visit Water Online’s Water Reuse Solutions Center.
Image credit: "irrigation," Wagner T. Cassimiro "Aranha" © 2010, used under an Attribution 2.0 Generic license: https://creativecommons.org/licenses/by/2.0/