Is Rancho Santa Margarita, CA tap water safe?
Supplied by Santa Margarita Water District · serves 165,275 people (56,472 connections) · Purchased surface water · EPA ID CA3010101
Data: U.S. EPA · How we read the data · How we check it
Buys water from El Toro Water District, Metropolitan Water District of SO. Cal., Irvine Ranch Water District, City of San Clemente, Moulton Niguel Water District, Trabuco Canyon 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 8 samples (2023–2025).
- Lithium
- Above screening levelHighest result 50.1 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 Santa Margarita Water District'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 (949) 459-6546. EPA: how to find it.
PFAS (“forever chemicals”)
EPA UCMR 5: 2 entry points tested Sep 2024 to Jun 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 8 of 8 samples. Highest result 50.1 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: 1.5 ppb (Dec 2018).
| Monitoring period | Lead (90th pct.) |
|---|---|
| Jan 2022 – Dec 2024 | 0 ppb |
| Jan 2019 – Dec 2021 | 0.9 ppb |
| Jan 2016 – Dec 2018 | 1.5 ppb |
Earlier results (9)
| Jan 2013 – Dec 2015 | 0 ppb |
| Jan 2010 – Dec 2012 | 0 ppb |
| Jan 2007 – Dec 2009 | 11 ppb |
| Jan 2004 – Dec 2006 | 0 ppb |
| Jan 2003 – Dec 2005 | 0 ppb |
| Jan 2003 – Dec 2003 | 5 ppb |
| Jan 2001 – Dec 2003 | 0 ppb |
| Jan 2000 – Dec 2000 | 5 ppb |
| Jan 1998 – Dec 2000 | 0 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
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 | 4.8 ppb | 300 ppb |
| Strontium | 1.2 ppm | 1.5 ppm |
| Molybdenum | 5.1 ppb | 40 ppb |
| Chromium-6 | 0.42 ppb | – |
| Chlorate | 1,500 ppb | 210 ppb |
| Vanadium | 3.2 ppb | 21 ppb |
Where it serves
Rancho Santa Margarita, Rancho Mission Viejo, San Clemente, Mission Viejo, San Juan Capistrano, Coto de Caza
ZIP codes the system reported serving: 92673, 92675, 92679, 92688, 92691, 92692, 92694
Nearby utilities
- El Toro Water District Lake Forest · 5 mi
- Moulton Niguel Water District Laguna Hills · 6 mi
- Irvine Ranch Water District Irvine · 10 mi
- City of San Clemente San Clemente · 13 mi
- City of Tustin Tustin · 14 mi
- Elsinore Valley Municipal Water District Lake Elsinore · 16 mi
Questions
Is Rancho Santa Margarita tap water safe to drink?
Most of Rancho Santa Margarita gets its water from Santa Margarita Water District. Santa Margarita 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 Rancho Santa Margarita water have PFAS?
EPA tested Santa Margarita Water District for 29 PFAS between Sep 2024 and Jun 2025 and none were detected above the reporting limits (about 2 to 20 ppt depending on the chemical).
What is the lead level in Rancho Santa Margarita water?
The most recent 90th-percentile lead result for Santa Margarita 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 CA3010101: violations, enforcement and inspections, straight from EPA.
- EPA UCMR 5 data: the PFAS and lithium results (search the file for PWSID CA3010101).
- EPA SDWIS download: the lead results, population and violation records we use.
- The utility's annual water quality report (Consumer Confidence Report): ask Santa Margarita Water District at (949) 459-6546, 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.