Is La Mesa, CA tap water safe?
Supplied by Helix Water District · serves 277,918 people (56,857 connections) · Surface water · EPA ID CA3710010
Data: U.S. EPA · How we read the data · How we check it
Buys water from Otay Water District, San Diego County Water Authority, City of San Diego, Padre Dam Municipal Water District, Lakeside Water District. Treated water bought from another system can carry that system's contaminants.
Summary
No federal limits exceeded in EPA data.
- PFAS
- Not detectedNone of 29 PFAS found above EPA's reporting limits in 4 samples (2023–2025).
- Lithium
- Above screening levelHighest result 26 ppb. EPA uses 10 ppb to decide what to study further. It is not a health limit, and there is no federal limit for lithium. About 1 in 4 systems tested were above it.
- Lead
- Below action level0 ppb (parts per billion) at the 90th percentile: 9 in 10 homes sampled were at or below it. Action level 15 ppb, falling to 10 ppb in Nov 2027. Monitoring period ending Dec 2024. Your home's pipes can make yours higher.
- Violations
- None health-basedNo health-based violations since 2016.
- Built before 1986, or not sure what your service line is made of? Check your service line and test your tap. Utility data can't show your pipes.
- Tested your own tap? Compare your result with these numbers. Moving? Compare this system with another.
- Read Helix Water District's 2026 water quality report (Consumer Confidence Report, from the utility). It lists every regulated contaminant tested, including ones not on this page. Questions: (619) 596-1362.
PFAS (“forever chemicals”)
EPA UCMR 5: 1 entry point tested Jan 2024 to Oct 2024. "Average" is the highest entry-point average (non-detects counted as zero), the way EPA compares UCMR 5 results to the limits. ppt = parts per trillion. These results do not determine compliance.
| Contaminant | Highest average |
|---|---|
| PFOA Not detected Limit 4 ppt | – |
| PFOS Not detected Limit 4 ppt | – |
| PFHxS Not detected Limit 10 ppt | – |
| PFNA Not detected Limit 10 ppt | – |
| HFPO-DA (GenX) Not detected Limit 10 ppt | – |
| Hazard Index (a combined score for PFHxS, PFNA, GenX and PFBS, where above 1 is over the limit) Not detected Limit 1 | – |
| PFBS Not detected Guideline 2,000 ppt | – |
| PFBA Not detected Guideline 6,000 ppt | – |
| PFHxA Not detected Guideline 3,000 ppt | – |
29 PFAS tested, 0 detected at least once. "Not detected" means below EPA's reporting limit (about 2 to 20 ppt depending on the chemical), not proven zero. PFAS not listed were not detected. The limits for PFHxS, PFNA, GenX and the Hazard Index were proposed for rescission in May 2026. That proposal is not final. Systems have until 2029 to meet the limits.
Lithium
Detected in 4 of 4 samples. Highest result 26 ppb. EPA's non-enforceable screening level is 10 ppb. Above screening level The screening level is how EPA decides what to study further, not a health limit. There is no federal limit for lithium and no filter is certified to remove it. About lithium.
Lead and copper
Latest 90th percentile: 0 ppb lead (Jan 2022 – Dec 2024). Below action level
Highest since 2016: 2.3 ppb (Dec 2021).
| Monitoring period | Lead (90th pct.) |
|---|---|
| Jan 2022 – Dec 2024 | 0 ppb |
| Jan 2019 – Dec 2021 | 2.3 ppb |
| Jan 2016 – Dec 2018 | 0 ppb |
Earlier results (9)
| Jan 2013 – Dec 2015 | 0 ppb |
| Jan 2010 – Dec 2012 | 0 ppb |
| Jan 2007 – Dec 2009 | 0 ppb |
| Jan 2006 – Dec 2006 | 5 ppb |
| Jan 2004 – Dec 2006 | 0 ppb |
| Jan 2003 – Dec 2005 | 0 ppb |
| Jan 2003 – Dec 2003 | 5 ppb |
| Jan 2000 – Dec 2000 | 5 ppb |
| Jan 1997 – Dec 1997 | 5 ppb |
Lead comes from pipes and fixtures, not the source water, so it varies home to home. The 90th percentile means 9 in 10 sampled homes were at or below it. More on lead.
Violations
No violations on record in EPA's Safe Drinking Water Information System.
Earlier EPA testing (2013–2020)
| Contaminant | Highest | Guideline |
|---|---|---|
| Manganese | 15.3 ppb | 300 ppb |
| Molybdenum | 4.3 ppb | 40 ppb |
| Vanadium | 2.5 ppb | 21 ppb |
| Strontium | 1.1 ppm | 1.5 ppm |
| Chromium-6 | 0.049 ppb | – |
| Chlorate | 36 ppb | 210 ppb |
Where it serves
La Mesa, Santee, El Cajon, Rancho San Diego, Spring Valley, Casa de Oro-Mount Helix, La Presa, Lemon Grove
ZIP codes the system reported serving: 91941, 91942, 91944, 91945, 91977, 91978, 92019, 92020, 92021, 92040, 92071, 92114, 92115
Nearby utilities
- Otay Water District Spring Valley · 4 mi
- Padre Dam Municipal Water District Santee · 6 mi
- City of San Diego San Diego · 7 mi
- Lakeside Water District Lakeside · 9 mi · PFAS above limit
- Sweetwater Authority Chula Vista · 10 mi · PFAS above limit
- California American Water – Coronado Coronado · 11 mi
Questions
Is La Mesa tap water safe to drink?
Most of La Mesa gets its water from Helix Water District. Helix Water District has no health-based violations since 2016. EPA testing found no PFAS above the federal limits. Federal data can't tell you about your own pipes: lead comes from service lines and plumbing, so test your tap if your home was built before 1986. For the official word, read the utility's annual Consumer Confidence Report.
Does La Mesa water have PFAS?
EPA tested Helix Water District for 29 PFAS between Jan 2024 and Oct 2024 and none were detected above the reporting limits (about 2 to 20 ppt depending on the chemical).
What is the lead level in La Mesa water?
The most recent 90th-percentile lead result for Helix Water District is 0 ppb, for the period ending Dec 2024. The federal action level is 15 ppb, falling to 10 ppb in November 2027. The 90th percentile means 9 in 10 homes sampled were at or below this number. Individual homes can be higher.
Check these numbers yourself
Every figure on this page comes from public EPA records. You don't have to take our word for it:
- EPA's own report for CA3710010: violations, enforcement and inspections, straight from EPA.
- EPA UCMR 5 data: the PFAS and lithium results (search the file for PWSID CA3710010).
- EPA SDWIS download: the lead results, population and violation records we use.
- Helix Water District's 2026 water quality report: the utility's own annual report, including contaminants EPA's national database doesn't carry (link checked Nov 14, 2026). Phone: (619) 596-1362.
- Helix Water District website
Found something that doesn't match? Tell us and we'll check it against EPA's records. How we check our data.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.