Is Walnut, CA tap water safe?
The short answer
None of the 3 utilities serving Walnut has a result above a legal limit or action level, or a health-based violation since 2016, in EPA’s and California’s records.
Walnut Valley Water District, which serves the most people here, has 1 result above EPA’s health benchmark. The worst: Lithium at 50.1 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 Walnut’s ZIP codes, from EPA’s estimates.
- Open report
Walnut Valley Water District
California · serves 100,941 people · about 8,800 in Walnut
1 result above EPA’s health benchmark. The worst: Lithium at 50.1 ppb, above EPA’s health benchmark.
No health-based violations since 2016
- Open report
Suburban Water Systems - San Jose
California · serves 170,523 people · about 2,400 in Walnut
3 results above the health goal and 1 result above EPA’s health benchmark. The worst: Lithium at 56 ppb, above EPA’s health benchmark. Hardness: hard to very hard depending on the source, 147 to 290 mg/L (8.6 to 17 grains per gallon).
No health-based violations since 2016
- Open report
Gswc - San Dimas
California · serves 56,564 people · about 300 in Walnut
1 result above EPA’s new limit, which takes effect in 2029, 4 results above the health goal and 1 result above EPA’s health benchmark. The worst: PFOS at 4.6 ppt, above EPA’s new limit, which takes effect in 2029. Hardness: very hard, typically 299 mg/L (17.5 grains per gallon).
No health-based violations since 2016
Water testing near Walnut
The 3 labs California certifies closest to Walnut, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Eurofins Pomona
Pomona, CA · about 4 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts, PFAS, radioactivity
Weck Laboratories, Inc.
City of Industry, CA · about 7 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts, PFAS, radioactivity
Enviro-Chem, Inc.
Pomona, CA · about 7 miles
Certified for metals
ZIP codes in Walnut
Which ZIP codes are in Walnut: 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 Walnut
Other towns in Los Angeles County with a page of their own.
What to do next
- Read Walnut Valley Water District’s full reportEvery result with its dates, the violations, and the certification claim that handles each finding.Open the report
- About LithiumWhat it does to health, where it comes from, and the certification claim that addresses it.About Lithium
- On a private well?No utility tests a well. A certified lab test is the first step.How to test well water