People in Los Osos, California who get water from the public supply are among residents whose systems have returned PFAS detections in EPA compliance testing.

Data: EPA SDWIS, CCR Reports, ECHO Last verified: 2026-05-14

PFAS in Los Osos Tap Water

PFAS has been detected in Los Osos, California drinking water at a maximum level of 0.018 ppt — below the EPA MCL of 4 ppt (PFOA/PFOS individually).

This analysis covers 7,677 residents across 2 ZIP codes in Los Osos.

Los Osos's overall water quality grade is B (81/100).

Is PFAS in Los Osos Water Safe?

If you live in an affected ZIP code, consider installing a reverse osmosis or granular activated carbon filter certified under NSF 53 / NSF 58 and testing your water independently.

PFAS Levels by ZIP Code

Average pfas level across Los Osos: 25 ppt

Health Effects of PFAS

• Increased risk of kidney and testicular cancer
• Thyroid disease and immune system suppression
• Reproductive problems and reduced fertility
• Elevated cholesterol and liver effects
• Developmental effects in infants and children

Health risk severity: High. Governed by the PFAS National Primary Drinking Water Regulation (2024).

How PFAS Gets Into Drinking Water

• Firefighting foam (AFFF) used at military bases and airports
• Industrial manufacturing (non-stick coatings, stain-resistant fabrics)
• Wastewater treatment plants that receive industrial discharge
• Landfill leachate from PFAS-containing consumer products

What to Do About PFAS in Los Osos Water

1. Install a reverse osmosis system (most effective — removes 90%+ of PFAS)
2. Granular activated carbon (GAC) filters remove some PFAS compounds
3. Look for NSF 53 or NSF 58 certification specifically tested for PFAS
4. Pitcher filters with activated carbon provide partial reduction

Look for filters certified under NSF 53 / NSF 58 for pfas removal.

Related

• PFAS — National Overview
• PFAS in California
• California Water Quality
• Los Osos Water Quality
• Check Your ZIP Code