Portola Valley, CA Water Safety: 55/100 (2026)
1 ZIP code · 1 water system · Updated 2026-06-03
Public water data for Portola Valley, CA reveals a split picture — tap water quality varies meaningfully by service area and the city's grade reflects that variability.
How Portola Valley Compares
Data: EPA SDWIS Last verified: 2026-06-03
What You Should Know About Portola Valley Water
- Homes built before 1986: 81% — older plumbing may contain lead solder.
- Estimated remediation: $2,200 per household.
- CDC health risk index: 9.58.
Who Supplies Your Water in Portola Valley
Consolidated water delivery characterizes Portola Valley, CA: among 1 system in federal records, one utility holds the dominant service position — carrying the rate-setting authority, the infrastructure obligations, and the EPA reporting burden for most residential addresses.
Overview
We track water quality and home safety data for 1 ZIP code in Portola Valley, California (population ~6,645), covering 1 community water system serving approximately 67,231 people region-wide.
No EPA violations recorded across any ZIP codes in Portola Valley — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Portola Valley: C (55/100)
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
Portola Valley water systems draw from: Surface water.
Lead & Copper
- Lead data: not yet available for Portola Valley
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 2 (Moderate Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 94028 | C | CITY OF PALO ALTO | 67,231 |
All ZIP Codes in Portola Valley
- 94028 [C]
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 Portola Valley
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 Portola Valley
With 81% 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 lead that enters tap water in older homes often comes not from the municipal supply but from the home's own plumbing — from solder used in copper joints before the 1986 federal ban, or from lead pipes installed before 1970. In Portola Valley, where the median build year is 1961, these older materials are widespread. More than half the residential stock predates the 1986 solder ban, and a significant fraction predates 1970 as well. For residents in those homes, the city-wide water quality picture is a less relevant frame than the specific materials inside their own walls and under their own street.
Over half of homes in Portola Valley 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 Portola Valley Homeowners
Setting Portola Valley remediation figures against its property market, the resulting ratio sits comfortably in the low tier — a classification that reflects the kind of household financial position where most homeowners can identify documented issues, schedule the work, and absorb the cost without it registering as a significant budget disruption.
Remediation costs in Portola Valley are relatively low compared to home values. The $1,200–$3,300 estimated range is a small fraction of median property value. Home values are 171% above the California average.
Lead Exposure Risk for Children in Portola Valley
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.
Although utility-side compliance with federal Lead and Copper requirements remains the system reference, that compliance does not extend down into interior plumbing. With 81% of Portola Valley stock built before the solder ban and aggregate readings at or beyond the action mark, a household-level sample becomes the practical way to close that information gap.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Flood & Climate Risk in Portola Valley
Flood history in Portola Valley spans 34 NFIP claims and 100% flood zone coverage — enough to place it in moderate-exposure territory where flood events are genuinely recurring rather than statistical outliers. That distinction matters for water quality assessment because the connection between flooding and water safety is not uniform across communities. In low-exposure areas, flooding rarely generates the conditions needed to compromise treatment or distribution infrastructure. In high-exposure areas, it can do so repeatedly. Moderate-exposure communities sit in between: flood events occur with enough frequency to make periodic infrastructure stress a reasonable concern, particularly for private well owners and residents in lower-elevation FEMA-designated zones.
Portola Valley has a moderate flood history with 34 FEMA claims averaging $29,398 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>$2,200</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.
What You Can Do in Portola Valley
- Test your water at home. City-level data shows averages — your tap may differ. NSF-certified test kits cost $20-40 and give results in days.
- Install a certified water filter. An NSF-certified pitcher or under-sink filter removes most common contaminants.
- Check your home's plumbing. With 81% of homes built before 1986, lead solder is a real possibility.
Deep Dive Reports
Detailed analysis for Portola Valley, CA