Is Cayucos, CA tap water safe?
The short answer
None of the 3 utilities serving Cayucos has a result above a legal limit or action level, or a health-based violation since 2016, in EPA’s and California’s records.
Morro Bay Pw Dept - Water Division, which serves the most people here, has 3 results above the health goal. The worst: Nitrate at 31.6 ppm, above the health goal. Health goals are stricter than legal limits and are not enforced.
A town can be served by more than one utility, and some homes are on private wells. The name on your water bill tells you which is yours, and your ZIP code narrows it down. They are listed by how many people each serves in Cayucos’s ZIP codes, from EPA’s estimates.
- Open report
Morro Bay Pw Dept - Water Division
California · serves 10,757 people · about 150 in Cayucos
3 results above the health goal. The worst: Nitrate at 31.6 ppm, above the health goal.
No health-based violations since 2016
- Open report
Cayucos Beach Mutual Water Company
California · serves 2,567 people · under 100 in Cayucos
2 results above the health goal. The worst: Arsenic at 2.3 ppb, above the health goal. Hardness: very hard, 430 mg/L (25.1 grains per gallon).
No health-based violations since 2016
- Open report
Morro Rock Mutual Water Co
California · serves 2,181 people · under 100 in Cayucos
2 results above the health goal. The worst: Arsenic at 1.8 ppb, above the health goal. Hardness: very hard, typically 377 mg/L (22 grains per gallon).
No health-based violations since 2016
What handles it
Each of these is certified, on a certifier’s listing, for a result above a line in Morro Bay Pw Dept - Water Division’s water, which serves the most people here. Another utility’s report names what handles its own results.
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Countertop reverse osmosis
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 4, 2026
Certified for: Nitrate, Arsenic
Aquasana SmartFlow Reverse Osmosis (AQ-SFRO2)
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Nitrate, Arsenic
Culligan 10-Cup Pitcher with ZeroWater Technology (ZEROP10)
Pitcher
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 401checked Oct. 9, 2026
Certified for: Nitrate
Water testing near Cayucos
The 3 labs California certifies closest to Cayucos, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
County of San Luis Obispo Public Health Laboratory
San Luis Obispo, CA · about 17 miles
Certified for bacteria
Fruit Growers Laboratory, Inc.
San Luis Obispo, CA · about 17 miles
Certified for bacteria
Abalone Coast Analytical, Inc.
San Luis Obispo, CA · about 18 miles
Certified for bacteria
Which ZIP codes are in Cayucos: Census 2020 relationship files. Which utilities serve them, and how many people: EPA SDWIS and EPA’s service area map. Each utility’s results: EPA UCMR 5, EPA SDWIS, and EPA’s and the state’s compliance monitoring, as its report lists them. How they are measured: methodology. Certified labs: California State Water Resources Control Board, ELAP accredited laboratories and their fields of accreditation; distances from the Census 2020 ZIP code tabulation area gazetteer.
Near Cayucos
Other towns in San Luis Obispo County with a page of their own.
What to do next
- Read Morro Bay Pw Dept - Water Division’s full reportEvery result with its dates, the violations, and the certification claim that handles each finding.Open the report
- Filters for NitrateRanked by certification and what they cost over five years.The best reverse osmosis systems, ranked
- On a private well?No utility tests a well. A certified lab test is the first step.How to test well water