South Dennis, MA Water Safety: 78/100 (2026)
1 ZIP code · 1 water system · Updated 2026-06-03
Tap water in South Dennis, MA scores well — low violation counts, above-average safety grade.
How South Dennis Compares
Data: EPA SDWIS Last verified: 2026-06-03
Key Facts for South Dennis Residents
- Average lead level: 0.001 mg/L.
- Homes built before 1986: 78% — older plumbing may contain lead solder.
- Estimated remediation: $2,100 per household.
- CDC health risk index: 12.93 — above typical levels.
South Dennis's Water Providers
Consolidated water delivery characterizes South Dennis, MA: 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 South Dennis, Massachusetts (population ~6,767), covering 1 community water system serving approximately 65,000 people region-wide.
No EPA violations recorded across any ZIP codes in South Dennis — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for South Dennis: B (78/100)
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
South Dennis water systems draw from: Groundwater.
Lead & Copper
- Average lead level (90th percentile): 0.0010 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)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 02660 | B | Dennis Water District | 65,000 |
All ZIP Codes in South Dennis
- 02660 [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.
South Dennis 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
South Dennis Infrastructure Age
With 78% 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
While newer cities carry lower aggregate plumbing risk from lead-era construction, South Dennis sits firmly in the older category. The median build year of 1974 indicates that more than half the housing stock was built before 1986, when lead solder was still legally used in residential copper plumbing — and a substantial portion likely predates 1970, when lead pipes were still commonly installed for service lines. These two thresholds together define the elevated plumbing risk environment that older housing cities carry, independent of what the municipal water supply delivers to the meter.
Over half of homes in South Dennis 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 South Dennis
In South Dennis, documented water and safety issues can be addressed without making a meaningful dent in home equity — the financial proportionality here is favorable, and the commitment fits within standard property planning frameworks.
Remediation costs in South Dennis 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 11% below the Massachusetts average.
South Dennis: 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.
Wherever 78% of local housing was built before solder rules changed — as is the case in South Dennis — a faucet-level sample closes the gap that aggregate utility data cannot.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
South Dennis: Flood History & Water Damage Risk
Taken together, South Dennis's 12 NFIP flood insurance claims and 100% FEMA flood zone coverage place it in the moderate range of exposure. That middle position has specific implications for water quality. The contamination pathways that flooding can open — surface water overwhelming treatment facility intake, floodwaters infiltrating private wells, distribution pressure changes creating backflow — are not constant risks in a moderate-exposure community. But they do become active during significant flood events, and the claim record here indicates enough of those events to make flood timing an occasional factor in local water quality conversations.
South Dennis has a moderate flood history with 12 FEMA claims averaging $1,628 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 South Dennis, MA