Gaithersburg, MD: High Radon Risk — 45/100 (2026)
9 ZIP codes · 3 water systems · Updated 2026-06-03
Monitoring data across Gaithersburg reveals a persistent pattern of below-average compliance in MD — multiple service areas carry documented health violations, and the data has shown little overall improvement over recent EPA reporting cycles.
How Gaithersburg Compares
Data: EPA SDWIS Last verified: 2026-06-03
Water Quality Map: Gaithersburg, MD
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Score Distribution
How ZIP codes in Gaithersburg score across all safety grades.
What You Should Know About Gaithersburg Water
- Estimated remediation: $2,122 per household.
- CDC health risk index: 10.24.
Who Supplies Your Water in Gaithersburg
In Gaithersburg, MD, residential water supply is distributed across multiple utilities rather than concentrated in one. The 3 leading providers out of 3 tracked systems each control their own infrastructure, file separate EPA compliance reports, and set independent rate schedules.
Overview
We track water quality and home safety data for 9 ZIP codes in Gaithersburg, Maryland (population ~144,191), covering 3 community water systems serving approximately 1,900,246 people region-wide.
No EPA violations recorded across any ZIP codes in Gaithersburg — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Gaithersburg: D (45/100)
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
Gaithersburg water systems draw from: Groundwater.
Lead & Copper
- Lead data: not yet available for Gaithersburg
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 1 (High Risk)
- Zone 1 (High): 9 ZIP codes
- Zone 2 (Moderate): 0 ZIP codes
- Zone 3 (Low): 0 ZIP codes
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 20877 | D | WASHINGTON SUBURBAN SANITARY COMMISSION | 1,900,000 |
| 20878 | D | WASHINGTON SUBURBAN SANITARY COMMISSION | 1,900,000 |
| 20879 | D | WASHINGTON SUBURBAN SANITARY COMMISSION | 1,900,000 |
| 20882 | D | WASHINGTON SUBURBAN SANITARY COMMISSION | 1,900,000 |
| 20883 | D | WOODBINE VILLAGE MOBILE HOME PARK | 150 |
| 20884 | D | GRANITE MOBILE HOME PARK | 96 |
| 20885 | D | GRANITE MOBILE HOME PARK | 96 |
| 20898 | D | GRANITE MOBILE HOME PARK | 96 |
| 20899 | D | WASHINGTON SUBURBAN SANITARY COMMISSION | 1,900,000 |
All ZIP Codes in Gaithersburg
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 Gaithersburg
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
Cost Context: What Remediation Means for Gaithersburg Homeowners
Setting Gaithersburg 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 Gaithersburg are relatively low compared to home values. The $1,389–$2,922 estimated range is a small fraction of median property value. Home values are 58% above the Maryland average.
Flood & Climate Risk in Gaithersburg
NFIP records stretching across multiple decades show Gaithersburg accumulating 36 claims and carrying 44% 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.
Gaithersburg has a moderate flood history with 36 FEMA claims averaging $3,108 per payout. 44% 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>$2,122</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 Gaithersburg
- 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. Homes built before 1986 may have lead solder in pipes. A licensed plumber can assess your risk.
- 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 Gaithersburg, MD