Walnut Creek, CA: 4 Violations — 74/100 (2026)
4 ZIP codes · 3 water systems · Updated 2026-06-03
Drinking water tracked for Walnut Creek 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 Walnut Creek Compares
Data: EPA SDWIS Last verified: 2026-06-03
Key Facts for Walnut Creek Residents
- Your city's water systems recorded 4 violations in the past 5 years.
- Average lead level: 0.002 mg/L.
- Homes built before 1986: 75% — older plumbing may contain lead solder.
- Estimated remediation: $2,100 per household.
- CDC health risk index: 10.72.
Walnut Creek's Water Providers
At present, 3 utilities serve the bulk of Walnut Creek, CA's residential water connections out of 3 systems active in the area, spread across independent providers with separate infrastructure and compliance obligations.
Overview
We track water quality and home safety data for 4 ZIP codes in Walnut Creek, California (population ~91,171), covering 3 community water systems serving approximately 1,640,845 people region-wide.
4 of 4 ZIP codes (100%) have recorded EPA violations. All violations are monitoring/reporting type.
Home Safety Score
Average Home Safety Score for Walnut Creek: B (74/100)
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
Walnut Creek water systems draw from: Groundwater.
Lead & Copper
- Average lead level (90th percentile): 0.0020 mg/L (EPA action level: 0.015 mg/L)
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 2 (Moderate Risk)
- Zone 1 (High): 0 ZIP codes
- Zone 2 (Moderate): 4 ZIP codes
- Zone 3 (Low): 0 ZIP codes
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Top Contaminants
| Contaminant | Category | Violations | ZIPs Affected |
|---|---|---|---|
| Stage 1 DBP Rule | Treatment Technique | 5 | 4 |
Areas with Most Violations
| ZIP Code | Safety Score | Violations | Health-Based | System |
|---|---|---|---|---|
| 94595 | B | 1 | 0 | EAST BAY MUD |
| 94596 | B | 1 | 0 | EAST BAY MUD |
| 94597 | B | 1 | 0 | EAST BAY MUD |
| 94598 | B | 1 | 0 | EAST BAY MUD |
All ZIP Codes in Walnut Creek
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.
Walnut Creek Community Health Snapshot
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
What's in Walnut Creek's Water?
Based on EPA violation records. Check your ZIP code report for system-specific contaminant data.
Walnut Creek Infrastructure Age
With 75% 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
When more than half a city's housing predates the 1986 federal ban on lead solder, plumbing-era lead risk becomes a citywide concern rather than an exception. Walnut Creek's median build year of 1975 places it squarely in that category.
Over half of homes in Walnut Creek 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.
How Remediation Costs Compare in Walnut Creek
At current valuations, Walnut Creek sits in the low remediation-share tier — the equity impact of fixing documented issues is proportionally minor.
Remediation costs in Walnut Creek are relatively low compared to home values. The $1,100–$3,400 estimated range is a small fraction of median property value. Home values are 69% above the California average.
Walnut Creek: Lead Risk & Vulnerable Populations
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.
After the federal action removing lead-bearing solder from new plumbing took effect, building practice shifted — but 75% of the Walnut Creek inventory predates that line. With aggregate samples near or beyond 0.015 mg/L, an in-home check moves out of the optional column into the standard list.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Walnut Creek: Flood History & Water Damage Risk
Over the multi-decade window covered by the National Flood Insurance Program, Walnut Creek has accumulated 180 claims — a total that suggests more than isolated flood exposure. With 100% of ZIP codes in designated flood zones, the water-quality implications of flooding move from hypothetical to periodically relevant: treatment intake can be compromised, wells can be infiltrated, and distribution backflow can occur.
Walnut Creek has a moderate flood history with 180 FEMA claims averaging $9,608 per payout. 100% 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>$2,100</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 Walnut Creek, CA