Is Blacklake, CA tap water safe?
The short answer
None of the 3 utilities serving Blacklake has a result above a legal limit or action level, or a health-based violation since 2016, in EPA’s and California’s records.
Nipomo Comm Services Dist, which serves the most people here, has 3 results above the health goal. The worst: Nitrate at 10.9 ppm, above the health goal. Health goals are stricter than legal limits and are not enforced.
The water from Nipomo Comm Services Dist is very hard, typically 294 mg/L (17.2 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 Blacklake’s ZIP codes, from EPA’s estimates.
- Open report
Nipomo Comm Services Dist
California · serves 13,771 people · about 200 in Blacklake
3 results above the health goal. The worst: Nitrate at 10.9 ppm, above the health goal. Hardness: very hard, typically 294 mg/L (17.2 grains per gallon).
No health-based violations since 2016
- Open report
Golden State Water Company - Nipomo
California · serves 4,512 people · under 100 in Blacklake
3 results above the health goal. The worst: Nitrate at 17 ppm, above the health goal. Hardness: soft to very hard depending on the source, 57 to 320 mg/L (3.3 to 18.7 grains per gallon).
No health-based violations since 2016
- Open report
Woodlands Development
California · serves 3,862 people · under 100 in Blacklake
1 result above the health goal. The worst: Uranium at 5.5 ppb, above the health goal. Hardness: soft to very hard depending on the source, 54 to 575 mg/L (3.2 to 33.6 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 Nipomo Comm Services Dist’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 Blacklake
The 3 labs California certifies closest to Blacklake, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Oilfield Environmental & Compliance Inc. (OEC)
Santa Maria, CA · about 6 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics
Abalone Coast Analytical, Inc.
San Luis Obispo, CA · about 17 miles
Certified for bacteria
Fruit Growers Laboratory, Inc.
San Luis Obispo, CA · about 18 miles
Certified for bacteria
ZIP codes in Blacklake
Which ZIP codes are in Blacklake: 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 Blacklake
Other towns in San Luis Obispo County with a page of their own.
What to do next
- Read Nipomo Comm Services Dist’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