One hundred and eighty-five Inverness households were instructed to boil their water for six days after a water main broke during the peak of last week’s storm, which dropped more than six and a half inches in town over the course of several days. 

At around 3 a.m. last Thursday, a small section of Woodhaven Road slid down the adjacent hillside, taking with it a segment of water main operated by the Inverness Public Utility District. The breach drained the two Tenney tanks and Connor tank, which together store 160,000 gallons of water at the top of Perth Way and on Vision Road. 

When the first customers awoke without water on Thursday morning and called the district, on-call employees moved to find the leak and quickly shut off the water. By Thursday around 11 a.m., the district had restored water flow, refilling the tanks. Yet due to a state mandate, IPUD instructed residents—via phone call to each home in the impacted area—to boil their water until further notice. 

When a main line depressurizes in the absence of water, occasionally the main can start siphoning sitting water back from homes through connector pipes. Wade Holland, who served as the district manager between 1985 and 2001 and who has been filling in since last fall while the district looks for a permanent hire, noted that the district requires check valves at household connections that allow water to flow only one direction, however. 

On Tuesday, after clearing the results from two sets of water samples, the California State Water Resources Control Board determined there was no contamination from bacteria, and the boil notice was lifted.

Luckily, the failure occurred at a dead end on an offshoot of the mainline that connects to just one house, a second home. Mr. Holland explained that the section, which dates back to the late ‘60s or early ‘70s and was made out of asbestos concrete, had not actually split: it had just fallen with the earth around it, breaking off at the connecting joints. (Ninety percent of the district’s piping has been replaced with polyvinyl chloride piping, or P.V.C.)

Mr. Holland, who has attempted to retire several times, said he has been working 11-hour days since the failure. One unexpected nicety: “We’ve had to put in a lot of work to call people,” he said about the effort to spread the information about the boil warning. “I’ve gotten to talk to customers I haven’t talked to in years.” 

Jim Fox, the district’s water system superintendent, estimated that around 150,000 gallons were lost in the failure, draining into a culvert that winds up in Tomales Bay.