Seneca, IL: High Radon Risk — 82/100 (2026)
1 ZIP code · 3 water systems · Updated 2026-06-03
Drinking water tracked for Seneca by IL 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 Seneca Compares
Data: EPA SDWIS Last verified: 2026-06-03
Seneca Water: The Quick Version
- Average lead level: 0.0013 mg/L.
- Homes built before 1986: 58% — older plumbing may contain lead solder.
- Estimated remediation: $1,800 per household.
- CDC health risk index: 13.79 — above typical levels.
Water Systems Serving Seneca
Federal drinking water records identify 3 systems in Seneca, IL. The leading 3 providers serve the largest share of residential connections, each operating as a separate entity with its own rate authority, infrastructure management, and EPA compliance obligations — so service conditions are not uniform city-wide.
Overview
We track water quality and home safety data for 1 ZIP code in Seneca, Illinois (population ~3,320), covering 3 community water systems serving approximately 26,414 people region-wide.
No EPA violations recorded across any ZIP codes in Seneca — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Seneca: B (82/100)
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
Seneca water systems draw from: Groundwater.
Lead & Copper
- Average lead level (90th percentile): 0.0013 mg/L (EPA action level: 0.015 mg/L)
- 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 |
|---|---|---|---|
| 61360 | B | Seneca | 2,353 |
All ZIP Codes in Seneca
- 61360 [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.
CDC Health Data for Seneca
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
How Old Is Seneca's Housing Stock?
With 58% 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
Viewed through the lens of construction era, Seneca is predominantly an older city — a median build year of 1972 puts most of the residential inventory in the range where pre-1986 plumbing materials were the standard.
Over half of homes in Seneca 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.
Seneca: Remediation Cost in Perspective
Low proportionality — that's the Seneca picture when remediation costs are placed against typical home equity.
Remediation costs in Seneca are relatively low compared to home values. The $1,200–$2,500 estimated range is a small fraction of median property value. Home values are 31% above the Illinois average.
Protecting Children from Lead in Seneca
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 58% of the Seneca 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.
Climate-Related Water Risk for Seneca
FEMA data shows 100% of Seneca's ZIP codes mapped into designated flood zones, paired with an NFIP record of 25 claims. That footprint places local flood exposure in the range where it warrants attention without rising to high-severity planning territory.
Seneca has a moderate flood history with 25 FEMA claims averaging $24,663 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>$1,800</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 Seneca, IL