The city of Bakersfield and California Water Service Co. on Sunday lifted the do-not-drink, do-not-use advisory issued Tuesday to 42 commercial customers south of Lake Truxtun after an oil company reportedly allowed pressurized natural gas and crude oil into the municipal water system.

A notice shared shortly before 4:30 p.m. said that after multiple rounds of intensive, one-way flushing, “test results have confirmed that it is safe to resume normal water use from the water distribution system.”

“On behalf of the city of Bakersfield and … (Cal Water) team, we apologize for the inconvenience this improper customer connection and backflow event has caused and thank you for your patience as we worked to restore the system to normal operations and confirm that water was safe to use and drink again. Protecting your health and safety is our highest priority.”

The end of the advisory signals a return to normalcy for companies that suffered substantial, if not total, interruptions. Those able to resume business had to rent portable toilets, in some instances, and rely on bottled water even for washing hands.

No residential properties were affected, but many health-care companies were, including surgery centers and an 86-bed rehabilitation hospital in the area including Office Park Drive, Commercial Way, Commerce Drive and Truxtun Avenue between Mohawk Street and Westside Parkway.

State oil regulators said Friday the contamination appears to have been caused by a valve or valves left partially open during a pipeline pressure test at an oil facility along Office Park Drive operated by Griffin Resources LLC, an oil producer with offices in Bakersfield and Ventura.

State records say Griffin was doing the work in response to an order by the California Geologic Energy Management Division, whose inspectors reported finding, in one area, numerous leaks at a series of wells and a flow line that was taken out of service years ago. At Griffin’s Office Park Drive location, where the water contamination apparently originated, CalGEM found electrical lines running through spilled oil partially covered with dirt, among other problems.

Anyone with questions about the advisory being lifted was advised to contact Cal Water’s Emergency Operations Center at 661-837-7243.