EPCOR – San Tan water quality
San Tan Valley, AZ · serves 87,435 people (26,986 connections) · Groundwater · Private · EPA ID AZ0411128
Data: U.S. EPA · How we read the data · How we check it
Summary
No federal limits exceeded in EPA data.
- PFAS
- Not detectedNone of 29 PFAS found above EPA's reporting limits in 14 samples (2023–2025).
- Lithium
- Above screening levelHighest result 185 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
- Resolved2 health-based violations since 2016, most recently Jan 2017. 2 required an urgent public notice within 24 hours (the kind behind boil-water notices), most recently Jan 2017. What to do if you get a notice.
- 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.
- Got a boil-water or do-not-drink notice? What each notice means and what to do.
- Pregnant, or mixing baby formula with tap water? Nitrate is most harmful to babies under 6 months, and boiling concentrates it. Consider bottled water or a filter certified for nitrate for formula, and ask your doctor. Health effects.
- Want to reduce what was found? Filters for these results.
- Tested your own tap? Compare your result with these numbers. Moving? Compare this system with another.
- Read EPCOR – San Tan's annual water quality report (Consumer Confidence Report). It lists every regulated contaminant tested and is usually on the utility's website or mailed with your bill, and you can also request it at (602) 722-4100. EPA: how to find it.
PFAS (“forever chemicals”)
EPA UCMR 5: 7 entry points tested Jul 2024 to Jan 2025. "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 14 of 14 samples. Highest result 185 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
| Monitoring period | Lead (90th pct.) |
|---|---|
| Jan 2022 – Dec 2024 | 0 ppb |
| Jan 2019 – Dec 2021 | 0 ppb |
| Jan 2016 – Dec 2018 | 0 ppb |
Earlier results (7)
| Jan 2013 – Dec 2015 | 0 ppb |
| Jan 2010 – Dec 2012 | 0 ppb |
| Jan 2009 – Dec 2011 | 3.2 ppb |
| Jan 2006 – Dec 2008 | 4 ppb |
| Jan 2004 – Dec 2006 | 0 ppb |
| Jan 2004 – Dec 2004 | 0 ppb |
| Jan 2003 – Dec 2003 | 3 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
| When | What happened |
|---|---|
| Jan 2016 – Jan 2017 2 times | A Nitrate sample was above the legal limit. Urgent public notice required What that means EPA record: Nitrate · Maximum Contaminant Level Violation, Single Sample · measured 12 mg/l (limit 10 mg/L) Resolved |
Health-based violations mean a contaminant exceeded a limit or a required treatment step was missed. Monitoring and reporting violations mean required tests or reports were late or missing, so the water's quality during that time is unknown. The total includes every violation in EPA's records, most of them paperwork.
Earlier EPA testing (2013–2020)
| Contaminant | Highest | Guideline |
|---|---|---|
| Manganese | 3.8 ppb | 300 ppb |
| Strontium | 1.5 ppm | 1.5 ppm |
| Molybdenum | 5 ppb | 40 ppb |
| Vanadium | 34 ppb | 21 ppb |
| Chromium-6 | 8.3 ppb | – |
| Chlorate | 34 ppb | 210 ppb |
Where it serves
San Tan Valley, Queen Creek
ZIP codes the system reported serving: 85140, 85142, 85143, 85254
Nearby utilities
- Town of Queen Creek Queen Creek · 5 mi
- Town of Gilbert Gilbert · 14 mi · PFAS above limit
- Arizona Water Company – Apache Junction Apache Junction · 15 mi
- City of Mesa Mesa · 18 mi
- City of Chandler Chandler · 18 mi
- Arizona Water Company – Pinal Valley Casa Grande · 22 mi
Questions
Is EPCOR – San Tan water safe to drink?
EPCOR – San Tan had 2 health-based violations since 2016, all since resolved. 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 EPCOR – San Tan water have PFAS?
EPA tested EPCOR – San Tan for 29 PFAS between Jul 2024 and Jan 2025 and none were detected above the reporting limits (about 2 to 20 ppt depending on the chemical).
What is the lead level in EPCOR – San Tan water?
The most recent 90th-percentile lead result for EPCOR – San Tan 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 AZ0411128: violations, enforcement and inspections, straight from EPA.
- EPA UCMR 5 data: the PFAS and lithium results (search the file for PWSID AZ0411128).
- EPA SDWIS download: the lead results, population and violation records we use.
- The utility's annual water quality report (Consumer Confidence Report): ask EPCOR – San Tan at (602) 722-4100, or see EPA's guide to finding it.
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.