A major boil water notice issued Wednesday is affecting thousands of residents across California’s Central Coast after bacteria was discovered in the drinking water supply. The advisory, which applies to the region’s “Five Cities” area, is expected to remain in place through Sunday as authorities continue testing and monitoring.
The affected communities include Arroyo Grande, Grover Beach, Oceano, Pismo Beach and Avila Beach—collectively served by the Zone 3 water system. Census data estimates roughly 46,000 people live across the five cities. Residents are being advised not to drink tap water unless it has been boiled for at least one minute, due to the presence of coliform bacteria detected in multiple water samples.
Why It Matters
Although the presence of coliform bacteria does not necessarily make the water unsafe to drink, it can indicate that other bacteria like E. coli are present. The detection of coliform bacteria has prompted state, county and local officials to conduct additional testing to ensure the water is safe to drink. In the meantime, people in the affected areas should boil their water before drinking it.
What To Know
The bacteria was detected in water samples collected on April 28 and April 29. The findings prompted the State Water Resources Control Board, Division of Drinking Water, County of San Luis Obispo Public Works Department, County Health Department and the Lopez Project water system to advise customers in Pismo Beach and other cities serviced by the Zone 3 system to use bottled water or tap water that has been properly boiled for drinking and cooking purposes.
“We will inform you when tests show that the water is safe to drink, and you no longer need to boil your water. We anticipate resolving the problem by Sunday, May 4, 2025, or sooner,” the advisory said.
Further instructions urge people to “be careful not to swallow any water when bathing or showering” and to “use caution when bathing babies and young children.” Ice made from tap water should not be used. However, laundry can be done as normal.
When reached for comment, the County of San Luis Obispo Public Works Department referred Newsweek to its most up-to-date press release, issued on Thursday afternoon.
“This is the first time a boil water notice has been triggered for the Lopez distribution system, and we are still working to identify the cause,” the update said. “Representatives from the State Division of Drinking Water will be on site Friday, May 2, 2025, to lead the investigation. Repeated positive samples of total coliform triggered a mandatory boil order by the State Division of Drinking Water. The repeated samples the County is collecting are showing a downward trend of this contaminant.”
Pismo Beach City Manager Jorge Garcia said in a Facebook video that daily water testing in Pismo Beach showed normal levels, but that the city is still following the county’s advice when it comes to the advisory.
The city will remain under the boil water advisory until the county and state confirm that it is safe to consume the water.
What People Are Saying
The Mayo Clinic, in a webpage about E. coli: “Signs and symptoms of E. coli … infection usually begin three or four days after exposure to the bacteria. But you may become ill as soon as one day after exposure to more than a week later. Signs and symptoms include: Diarrhea, which may range from mild and watery to severe and bloody … Stomach cramping, pain or tenderness … Nausea and vomiting, in some people.”
Garcia said in the video about the advisory: “It’s important not to count on filtered water as reliable way to consume the water. Having a water filter or a reverse osmosis system is not sufficient.”
What Happens Next
The county anticipates the issue will be resolved by Sunday. In the meantime, customers must either boil the water or treat it to make it safe by disinfecting it with bleach or tablets. Instructions on how to do so can be found on the Pismo Beach website. Pets also can be affected by bacteria, and bottled water or boiled and then cooled water should be used for them.
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