But the statewide water emergency could make that practice a thing of the past.
When Mayor Ed Lee declared a local drought emergency Feb. 10 and asked all water users in The City to cut back usage by 10 percent, he also put San Francisco on notice: It’s time to start looking at nonpotable water for uses like street cleaning.
The City’s plentiful water supply is both an insurance against drought and a moneymaker: for every gallon of water used in The City, up to 4 gallons of water are sold to the water districts in Santa Clara and San Mateo counties.
San Francisco’s gross water use is about 88 gallons per customer per day, which is less than one-half of the statewide average of 197 gallons.
But relying on the Hetch Hetchy Reservoir — from which comes the pristine Sierra snowmelt that’s piped in from Yosemite National Park more than 150 miles away — has also meant that other water districts in the Bay Area and California are ahead of San Francisco with ambitious water-recycling goals. However, every major city in the state also uses at least some drinking water to clean streets.
It’s not clear exactly how much drinking water is dumped on streets in San Francisco. The data were not immediately available, though municipal water use is about 6 percent of the total.
City agencies are meeting to hash out solutions, with more summits scheduled for later this month.
But for now, the Department of Public Works has no realistic alternative to the Tuolumne River water delivered from the Hetch Hetchy Reservoir.
There’s treated wastewater available right now at the Oceanside and Southeast treatment plants, but there’s only one hookup per plant.
In addition to wanting to avoid a traffic crush of street sweepers at each plant, it’s not even certain if the hookups on the DPW’s street cleaning trucks would be compatible with the water hookups on-site, according to the San Francisco Public Utilities Commission.
In October 2012, The City began buying recycled water from Daly City to use on city-owned golf courses. That was the first use of recycled water since 1978, when new state regulations led a water recycling plant in Golden Gate Park to shut down.
Work is underway to make about 4 million gallons of recycled water available per day. An environmental impact report on a Westside recycling plant is due this spring, and the SFPUC is looking for a suitable site on the east side to build a plant there.
In Los Angeles, a mix of potable water from fire hydrants and some of the 7.1 million gallons of treated wastewater available daily is used to wash streets, according to officials there.
Los Angeles is aiming to have 52 million gallons a day of recycled water available by 2035.
San Jose set a goal of recycling 40 million gallons of its daily wastewater by 2022. Currently, the city produces 13.7 million gallons of recycled water daily.
Across the Bay, the East Bay Municipal Utility District can produce up to 9 million gallons of recycled water a day, according to the agency.
Nearly all of that water goes to Chevron, which uses the recycled water for cooling towers and for boilers at its oil refinery in Richmond.
Most public works agencies in the East Bay do use drinking water for cleaning purposes, though that could change this year.
Mandatory rationing of drinking water during a drought in 2008 led to the district providing recycled water for municipal crews.
The EBMUD could declare mandatory rationing again in April.
10 percent: amount all city water users were asked to cut their usage by
88 gallons: used daily by each customer in city
197 gallons: used daily by average state water user
4 gallons: sold to water districts in San Mateo and Santa Clara counties for every 1 gallon used in The City