DALLAS – A dozen fire hydrants in North Oak Cliff and West Dallas have been open since late last week – spraying 500,000 gallons of water down the drain each day as the city cleans water lines.

“The most important thing you need to know is this is required by state,” said Randall Payton, assistant director at Dallas Water Utilities.

This is the latest neighborhood in the city’s regular maintenance of water mains.

“Personnel strategically close valves to direct water down a single water main creating a velocity that can scour the internal pipe wall. Though these actions may result in brief periods during which customers may observe discoloration in tap water, the water remains safe to drink,” said Payton.

It’s called unidirectional flushing and is underway in some part of the city almost all the time, he added, to maintain water quality.

The process is a common practice across the country and required in this state by the TCEQ, Texas Commission on Environmental Quality.

But with a dozen hydrants open in North Oak Cliff, 500,000 gallons of water is lost each day, said Payton.

Considering the cleaning began late last week and will wrap up likely on Tuesday that could be 2.5 million gallons of water wasted just in this one community.

Two years after a drought across much of the state, why doesn’t Dallas Water Utilities recapture the lost water by piping it into trucks for another use such as landscaping, city pools, or something else rather than let it go down the drain?

“In some areas you’ll notice we hard pipe it and run it back to the sanitary sewer,” said Payton. “It’s very hard to recollect that water but we do when we can.”

Still, in 2012, city council passed a Water Conservation Ordinance which threatens fines of up to $2,000 for anyone repeatedly caught irrigating their lawns with sprinkler systems more than twice a week, letting sprinklers water driveways, sidewalks and streets or wasting water by allowing runoff onto a street or other drainage area when you’re watering.

“Aggressive water conservation efforts are critical to demonstrate that our region is using existing resources responsibly,” according to SaveDallasWater.com.

Utilities in other states agree that collecting the discharged water is difficult.

“Recapturing water discharged through flushing is difficult and not cost-effective,” explains said the City of Livermore, Calif. in an on-line FAQ. “Using water trucks to collect and transport the water is neither cost effective, nor mechanically possible considering the necessary flow velocity and duration to adequately flush the system.”

But a New Mexico company discovered a market for a mobile flushing system on the back of a truck that prevents so much waste.

In California, where water conservation is a higher priority, some cities are investing in the Neutral Output Discharge Elimination System or NO-DES trucks which drastically reduces the amount of water sent down the drain.

The Soquel Creek Water District in Calif. tested a NO-DES unit last year, according to the Santa Cruz Sentinel in July 2015. The district said it was able to save tens of thousands of gallons of water.

This month, the Capitola Soquel Times reported that the water district purchased the truck for $380,000.

Purchasing several of those vehicles to take over the required water main flushing in Dallas could be a pricey proposition with the city’s 4,930 miles of potable water mains. Especially since the state is out of a drought and the city faces more pressing financial issues like poor roads and pension problems.