Darien, CT: High Radon Risk — 35/100 (2026)
1 ZIP code · 3 water systems · Updated 2026-06-03
Darien, CT water systems: poor compliance record, lower-tier safety grade.
How Darien Compares
Data: EPA SDWIS Last verified: 2026-06-03
What You Should Know About Darien Water
- Homes built before 1986: 74% — older plumbing may contain lead solder.
- Estimated remediation: $3,600 per household.
Who Supplies Your Water in Darien
Residential water service in Darien, CT is divided among 3 separate utilities, drawn from 3 systems on file with federal regulators.
Overview
We track water quality and home safety data for 1 ZIP code in Darien, Connecticut (population ~21,683), covering 3 community water systems serving approximately 370,726 people region-wide.
No EPA violations recorded across any ZIP codes in Darien — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Darien: F (35/100)
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
Darien water systems draw from: Groundwater.
Lead & Copper
- Lead data: not yet available for Darien
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 1 (High 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 |
|---|---|---|---|
| 06820 | F | AQUARION-EASTERN FAIRFIELD COUNTY | 351,756 |
All ZIP Codes in Darien
- 06820 [F]
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.
Housing & Infrastructure in Darien
With 74% 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
Federal plumbing rules changed in two stages — lead pipes were phased out before 1970, and lead solder was banned in 1986 — but in Darien, where the median build year is 1954, most of the housing was already in place before those rules took effect. The materials installed under older standards remain embedded in a substantial portion of the residential inventory today.
Over half of homes in Darien 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 Darien Homeowners
In Darien, property values comfortably outpace what documented remediation typically costs — the equity share is proportionally low.
Remediation costs in Darien are relatively low compared to home values. The $2,400–$4,800 estimated range is a small fraction of median property value. Home values are 323% above the Connecticut average.
Lead Exposure Risk for Children in Darien
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 74% of Darien 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 Darien
Measured against the full NFIP dataset, Darien's flood record stands out: 625 claims accumulated over decades and 100% of ZIP codes inside FEMA-designated boundaries add up to a high-exposure profile where water infrastructure has faced recurrent stress.
Darien has a significant flood history with 625 FEMA flood insurance claims on record, averaging $34,108 per claim. With 100% of ZIP codes in FEMA-designated flood zones, flood risk is a major concern for homeowners and water quality.
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>$3,600</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 Darien
- 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 74% of homes built before 1986, lead solder is a real possibility.
- Review your water system's CCR. Your utility publishes an annual Consumer Confidence Report with detailed test results. Request it or find it online.
Deep Dive Reports
Detailed analysis for Darien, CT