E. coli found in south San Luis Obispo County water supply

May 1, 2025

By KAREN VELIE

The water supply for five communities in San Luis Obispo County is contaminated with coliform bacteria, or E. coli, leading to a boil water order for cooking and drinking water.

After the contamination was detected in treated water from Lopez Lake, the county issued a boil water order for Arroyo Grande, Grover Beach, Pismo Beach, Avila Beach, and Oceano. The bacteria was discovered during routine testing.

The water is contaminated through a transmission line. The county is estimating the ongoing water contamination will be corrected by Sunday.

Boil water order

• Do not drink the water without boiling it first.
• Boil all water for one minute.
• Let water cool before drinking.
• Use boiled or bottled water for drinking, brushing teeth, and food preparation.
• Boiling water kills bacteria and other organisms in the water.

If you are unable to boil your water:

• For clear water, use eight drops (1/8 teaspoon) of household unscented liquid bleach for one gallon of water.
• For cloudy water, filter through a clean cloth and use 16 drops (1/4 teaspoon) of bleach for 1 gallon of water.
• Mix well.
• Allow to stand for 30 minutes before using.
• Water may taste or smell like chlorine. This means disinfection has occurred.

Symptoms caused by drinking contaminated water may include stomach cramps, diarrhea, and vomiting. Symptoms generally begin two to four days after drinking the contaminated water.

Most people will recover at home without medical care but, in some cases, illness can be severe and will require medical treatment. Young children and older adults are more at risk of severe illness.

Seek medical care right away if you experience any of these more severe symptoms:

• Diarrhea or vomiting more than two days
• Bloody stool or bloody urine
• Fever higher than 102°F
• Signs of dehydration such as little or no peeing, having very dark pee, being very thirsty, having a dry mouth or throat, feeling dizzy or lightheaded, and crying without tears
• Unexplained bruising or rash with tiny red spots
• Feeling extremely tired or not alert

If you have mild symptoms and are recovering at home, it is important to stay well-hydrated.