Is Los Ranchos, CA tap water safe?
The short answer
Neither of the 2 utilities serving Los Ranchos has a result above a legal limit or action level, or a health-based violation since 2016, in EPA’s and California’s records.
San Luis Obispo Water Department, which serves the most people here, has 2 results above the health goal. The worst: Uranium at 10.3 ppb, above the health goal. Health goals are stricter than legal limits and are not enforced.
The water from San Luis Obispo Water Department is hard to very hard depending on the source, 174 to 455 mg/L (10.2 to 26.6 grains per gallon). How California’s water compares.
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 Los Ranchos’s ZIP codes, from EPA’s estimates.
- Open report
San Luis Obispo Water Department
California · serves 49,534 people · about 1,200 in Los Ranchos
2 results above the health goal. The worst: Uranium at 10.3 ppb, above the health goal. Hardness: hard to very hard depending on the source, 174 to 455 mg/L (10.2 to 26.6 grains per gallon).
No health-based violations since 2016
- Open report
Golden State Water Company - Edna
California · serves 1,495 people · under 100 in Los Ranchos
4 results above the health goal. The worst: Nitrate at 14 ppm, above the health goal. Hardness: very hard, typically 430 mg/L (25.1 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 San Luis Obispo Water Department’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: 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: Arsenic
Brondell Capella RC250 Reverse Osmosis System
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Arsenic
Water testing near Los Ranchos
The 3 labs California certifies closest to Los Ranchos, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Fruit Growers Laboratory, Inc.
San Luis Obispo, CA · about 3 miles
Certified for bacteria
County of San Luis Obispo Public Health Laboratory
San Luis Obispo, CA · about 3 miles
Certified for bacteria
Abalone Coast Analytical, Inc.
San Luis Obispo, CA · about 3 miles
Certified for bacteria
ZIP codes in Los Ranchos
Which ZIP codes are in Los Ranchos: 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 Los Ranchos
Other towns in San Luis Obispo County with a page of their own.
What to do next
- Read San Luis Obispo Water Department’s full reportEvery result with its dates, the violations, and the certification claim that handles each finding.Open the report
- About UraniumWhat it does to health, where it comes from, and the certification claim that addresses it.About Uranium
- On a private well?No utility tests a well. A certified lab test is the first step.How to test well water