Southern Californians who reside near the mountains, hillsides or canyons live with the risk of a wildfire burning down their homes.
But rarely do they think about a fire contaminating their drinking water. Perhaps they should.
Just ask residents of Ventura, Santa Paula and Ojai, who must boil their tap water before drinking it, cooking with it or brushing their teeth, the result of the powerful Thomas fire that knocked out portions of their water system Tuesday and grew to 96,000 acres by Thursday.
The order affects more than 120,000 people who could become infected by bacteria causing intestinal illnesses if they drink tap water without boiling it first. The boil-water alert went into effect Tuesday and may last about a week or less, said Ventura Water spokesman Craig Jones.
Fire’s new threat: water supply
Possible contamination to the water supply in California communities slammed by wildfires is a growing concern. The breakdown of water systems — mostly occurring in smaller cities and among isolated, mutual water districts — is happening today and may become more common in the future as infrastructure ages and wildfires intensify due to global climate change.
“It speaks to the reality we live in, in Southern California. You have to be prepared for the worst,” said Bob Muir, spokesman for the Metropolitan Water District, which supplies about 45 percent of the water to Southern California.
While MWD has not had any problems with its pipes, pumps and local reservoirs during the recent firestorms, the same cannot be said of some smaller water providers.
A fire-related power outage shut off the pumps that moved water uphill to reservoirs in Ventura County. At least one reservoir went dry, causing a severe drop in water pressure. That created negative pressure, allowing the possibility of contaminants to be sucked into the system.
“Any time you depressurize the water system, there are contamination concerns,” said Jeff Densmore, district engineer for the Division of Drinking Water of the State Water Resources Control Board.
This can create a siphon-effect, whereby water from a garden hose attached to a dirty pool can reverse and flow into the city’s drinking water pipes, he explained.
The lack of pressure was made worse by firefighters pulling thousands of gallons per minute from fire hydrants, faster than the pumps could keep up, he said. “With no water pressure, we assume the worst. We tell customers to boil their water,” he…