The SFPUC held a news conference in response to a Thursday San Francisco Examiner story citing that levels of nitrate and coliform bacteria in groundwater exceeded U.S. Environmental Protection Agency drinking water standards.
Steve Ritchie, the utility’s assistant general manager for water, said the test was conducted in 1988 with samples taken from two “poorly constructed wells” that was “not representative of the groundwater basin as far as we’re concerned.”
“The sample that was taken was accurate, but that was a well that was poorly constructed in Golden Gate Park; that was not a good well to use,” Ritchie said. “It was done in a study a long time ago. We’ve done substantial more work since then and it’s perfectly safe to drink.”
Four groundwater wells are slated to start producing water within the next two years, in part to give The City a backup in the event of a continued drought or major earthquake. When the groundwater system begins producing water, it will be mixed with existing water supplies in a 10 percent to 90 percent ratio, respectively.
The groundwater will go through three-steps that ensure it meets drinking quality standards – the natural filtering characteristics of the soil, a disinfecting process and the blending with Hetch Hetchy water, which comes from Sierra Nevada snowmelt.
Nearly 60 percent of San Francisco will get the new blended water.
“I bet if you walked across the street from where the blends were, you would not be able to tell the diffidence in the quality of water coming from the tap,” Ritchie said.
Currently, San Francisco tap water is a mix of about 85 percent from Hetch Hetchy and 15 percent from reservoirs in the East Bay and Peninsula. This will be the first time The City draws from groundwater for drinking purposes since the 1930s, but it is a system many municipalities across the state and nation have used for decades.
“San Francisco itself used groundwater as part of its supply back in the 1930s,” Ritchie said. “So this is a good resource for all of us that we’re looking forward to taking advantage of again.”
Having a “diversity” of water sources, he said, will be “a great asset to San Francisco” -- especially in the event of an emergency or drought.
Using groundwater will boost The City’s water supply by 6 percent.