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Is San Marcos, CA tap water safe?

2 utilities serve San Marcos, by EPA’s records. Here is what EPA’s and California’s records show for each, against the legal limits and the stricter health goals.

Matched to your utility using EPA records.

The short answer

Neither of the 2 utilities serving San Marcos has a result above a legal limit or action level, or a health-based violation since 2016, in EPA’s and California’s records.

Vallecitos WD, which serves the most people here, has 1 result above EPA’s health benchmark. The worst: Lithium at 52 ppb, above EPA’s health benchmark. A health benchmark is a level EPA screens with, not a legal limit.

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 San Marcos’s ZIP codes, from EPA’s estimates.

Water testing near San Marcos

A utility tests the water it sends out. A test of your own tap shows what your pipes add, and on a private well it is the only test there is. It takes a lab California certifies.

The 3 labs California certifies closest to San Marcos, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Applied Industrial Microbiology, Inc.

    Vista, CA · about 4 miles

    Certified for bacteria, nitrate

    (760) 295-0430

  • Alpha Analytical Laboratories, Inc. - San Diego

    Vista, CA · about 5 miles

    Certified for bacteria, nitrate, minerals and other inorganics

    (760) 536-3352

  • EMSL Analytical, Inc.

    San Diego, CA · about 21 miles

    Certified for bacteria

    (800) 220-3675

All 145 certified labs for California

ZIP codes in San Marcos

Which ZIP codes are in San Marcos: 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 San Marcos

Other towns in San Diego County with a page of their own.

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