Flushed: More Information Floods Forth on City's Roaring Hydrants

Joe Eskenazi

Whitewater!

​The other day, we wrote about the proliferation of Water Department employees cracking open Mission Bay's fire hydrants, letting 'em rip, and then cooling their heels for up to three hours or more while untold quantities of Hetch Hetchy water gushed into the sewers.

Sure it was fun to look at -- but three hours? We were told this is what it takes to ensure sedimentation doesn't gum up the fire hoses. Every once in a while "unidirectional flushing" is a necessity -- even if it does induce car wash-like scenes on city streets.

Yesterday, Public Utilities Commission spokesman Tyrone Jue told us that the de-facto power-washing of Mission Bay's sidewalks has more uses than simply preventing clogged fire lines. It's also keeping you from drinking filth. This is the logical aftermath of the dreaded "brown water" complaints.

"It's not just sedimentation issues, but water quality issues. If you leave water in a glass, it becomes stale. The same things happens in a water system if there's not enough usage," says Jue. "So, typically, around holiday time, there's less usage in the Downtown area, so it is possible the water is becoming stale."

The University Mound system workers have been flushing out serves the Northeast of San Francisco and provides around 40 percent of the city's water.

Jue noted that the PUC recently flushed piplines out in the Richmond District: "We put up notifications and signs alerting people we were going to be doing it." That didn't seem to happen out here in Mission Bay -- but, to be fair, you might be able to land a spaceship in parts of Mission Bay without people noticing.

Jue confirmed that population density and traffic is a factor in choosing where to flush the system. "We would want to avoid Nob Hill or Russian Hill," he says.

No word yet on our other queries: Do you really need to flush the system for three hours? And how much water gushes out of a hydrant every minute?