Mission Viejo, CA Water Safety: 71/100 (2026)
3 ZIP codes · 6 water systems · Updated 2026-06-03
Drinking water tracked for Mission Viejo by CA authorities posts above-average scores — the majority of systems are free from health-based exceedances and the city's grade sits above the state median.
How Mission Viejo Compares
Data: EPA SDWIS Last verified: 2026-06-03
What You Should Know About Mission Viejo Water
- Homes built before 1986: 68% — older plumbing may contain lead solder.
- Estimated remediation: $1,700 per household.
- CDC health risk index: 10.23.
Who Supplies Your Water in Mission Viejo
Throughout Mission Viejo, CA, water comes from one of 3 primary utilities out of 6 total systems — independent providers with different rate structures, infrastructure, and compliance records that vary across the service territory.
Overview
We track water quality and home safety data for 3 ZIP codes in Mission Viejo, California (population ~93,186), covering 6 community water systems serving approximately 888,468 people region-wide.
No EPA violations recorded across any ZIP codes in Mission Viejo — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Mission Viejo: B (71/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
Mission Viejo water systems draw from: Surface water.
Lead & Copper
- Lead data: not yet available for Mission Viejo
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 3 (Low Risk)
- Zone 1 (High): 0 ZIP codes
- Zone 2 (Moderate): 0 ZIP codes
- Zone 3 (Low): 3 ZIP codes
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 92690 | C | EL TORO WATER DISTRICT | 51,800 |
| 92691 | B | MOULTON NIGUEL WATER DISTRICT | 170,236 |
| 92692 | B | EL TORO WATER DISTRICT | 51,800 |
All ZIP Codes in Mission Viejo
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.
Health Outcomes in Mission Viejo
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
Housing & Infrastructure in Mission Viejo
With 68% of homes built before 1986, lead solder in plumbing is a potential concern. The EPA banned lead solder in 1986, but many older homes retain original plumbing.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
The character of Mission Viejo's housing stock is one of deep historical layering — a median build year of 1979 signals a city built largely before the plumbing era changes of 1986 and 1970. Lead-soldered copper joints and, in the oldest properties, lead service lines are commonly present in this inventory. That context shapes what individual water testing may reveal, particularly in neighborhoods where the oldest housing is concentrated.
Over half of homes in Mission Viejo were built before 1986, when lead solder was banned. Older plumbing may leach lead into drinking water, especially with corrosive water chemistry.
Source: U.S. Census Bureau ACS B25034.
Cost Context: What Remediation Means for Mission Viejo Homeowners
What does remediation cost in financial context for Mission Viejo homeowners? Proportionally very little — the equity share here is low, and addressing documented issues is a manageable planning question rather than a material financial burden.
Remediation costs in Mission Viejo are relatively low compared to home values. The $1,100–$2,600 estimated range is a small fraction of median property value. Home values are 33% above the California average.
Lead Exposure Risk for Children in Mission Viejo
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
Confirming what arrives at a specific faucet is something utility-side averages cannot do. With 68% of Mission Viejo stock built before the lead-solder ban and citywide monitoring at or beyond the regulatory mark, a tap-level kit fits the standard diligence picture.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Flood & Climate Risk in Mission Viejo
The NFIP claim record for Mission Viejo — 13 filed incidents — reflects genuine, recurring flood exposure rather than an isolated event or two. When a community accumulates flood claims at this volume and carries 67% of its ZIP codes inside FEMA-designated zones, flood history starts to factor into water quality planning in ways it doesn't for lower-exposure areas. Flooding introduces specific contamination pathways — runoff overwhelming treatment facility intake, surface water infiltrating private wells, and pressure disruptions in distribution systems allowing backflow — all of which become more relevant as flood frequency increases.
Mission Viejo has a moderate flood history with 13 FEMA claims averaging $11,223 per payout. 67% of ZIP codes fall within FEMA flood zones. Flood events can contaminate drinking water and overwhelm treatment systems.
How flooding affects water quality: Flood events can introduce sewage, agricultural runoff, and industrial chemicals into water supplies. Even after floodwaters recede, contamination can persist in wells and aging infrastructure. Flood damage can add significantly to the estimated <strong>$1,700</strong> remediation cost per household.
Residents in flood-prone areas should consider flood insurance even outside FEMA zones — over 25% of flood claims come from low-to-moderate risk areas. After any flood event, test your water before drinking.
Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.
Deep Dive Reports
Detailed analysis for Mission Viejo, CA