Marshall, CA Water Safety: 73/100 (2026)
1 ZIP code · 2 water systems · Updated 2026-06-03
Based on current monitoring, Marshall holds an above-average drinking water safety record for CA — violations are infrequent and typically minor when they do appear.
How Marshall Compares
Data: EPA SDWIS Last verified: 2026-06-03
What You Should Know About Marshall Water
- Homes built before 1986: 95% — older plumbing may contain lead solder.
- Estimated remediation: $1,200 per household.
- CDC health risk index: 10.78.
Who Supplies Your Water in Marshall
Residential addresses in Marshall, CA are served by 2 primary water providers out of 2 systems in federal records. Each system maintains separate infrastructure and files its own EPA compliance reports, so service conditions are not uniform across the city.
Overview
We track water quality and home safety data for 1 ZIP code in Marshall, California (population ~275), covering 2 community water systems serving approximately 63,136 people region-wide.
No EPA violations recorded across any ZIP codes in Marshall — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Marshall: B (73/100)
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
Marshall water systems draw from: Surface water.
Lead & Copper
- Lead data: not yet available for Marshall
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 3 (Low Risk)
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 94940 | B | NORTH MARIN WATER DISTRICT | 61,691 |
All ZIP Codes in Marshall
- 94940 [B]
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 Marshall
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 Marshall
With 95% 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
For residents trying to assess tap water risk in Marshall, the median build year of 1902 is the starting context. It signals that a majority of homes were constructed before 1986 — the year federal rules prohibited lead solder in new plumbing — and that a significant share likely predates 1970, when lead pipes were still a common choice for residential service connections. Neither risk tier is rare in this housing inventory.
Over half of homes in Marshall 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.
Lead Exposure Risk for Children in Marshall
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.
If 95% of the Marshall inventory comes from before the federal ban on lead-bearing solder — and if utility samples sit at or near 0.015 mg/L — the gap between citywide averages and one specific faucet becomes a practical concern rather than a theoretical one. That is why one-home reads exist as a separate measurement. A certified filter through retailer networks addresses confirmed exposure where it appears in a household.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Flood & Climate Risk in Marshall
NFIP records stretching across multiple decades show Marshall accumulating 8 claims and carrying 100% of its ZIP codes inside FEMA flood zones — evidence of meaningful exposure that extends beyond isolated incidents. The mechanisms linking flooding to water quality haven't changed: treatment facilities can be overwhelmed, wells can be infiltrated, and distribution systems can experience backflow. For a community at this exposure level, those mechanisms shift from hypothetical to periodically relevant.
Marshall has a moderate flood history with 8 FEMA claims averaging $17,091 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>$1,200</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 Marshall, CA