Next Question: Why do cities drain fire hydrants?

About 1,000 gallons of water is flushed out of the hydrants. Is that a waste?

KUSA - Our Next Question comes from someone concerned about the wise usage of water.

“Why do cities "drain" fire hydrants and just let the water run right down into the sewer? It seems like such a waste. (…) Would love to know why they do it in the first place, and why aren't we saving or redirecting the water somehow?”

That was the question sent in to us from viewer Jessica. And Next is nothing, if not ready to provide answers. Denver Water was there to help.

It’s a matter of water quality. During the winter, water sits at dead ends and cul-de-sac, growing stale and stagnated. Hydrants are flushed to bring water quality back up to what it should be for the summer.

Denver Water also flushes water upon request from a fire department or insurance company, to make sure the fire hydrant has enough pressure to actually fight a fire. 

South Metro Fire Rescue spokesman Eric Hurst told us in an email that what we don’t see is what a hydrant looks inside like when it’s first open. It’s rusty, it might even have debris in it, but this clears up once the water gets flowing.

This is why firefighters always let the water flow out of the hydrant before they hook the hose up to fight a fire. Otherwise, rocks and trash could clog up the hoses or even destroy the fire engine pump, he said.

And as for waste… well, a hydrant takes about 10 to 15 minutes to flush about 1,000 gallons of water, Denver Water told us.

That sounds like a lot of wasted water flowing down your street into the sewer, but really it’s only about 0.01 percent of Denver Water’s total annual consumption. In other words, one percent of one percent of the yearly water usage.

If that still sounds like too much wasted water to you, you can ask that the water be diverted to onto your lawn.

Have a question about something you've seen? Reach out to us by email, on Facebook or Twitter.

© 2017 KUSA-TV


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