Marriottsville, MD: High Radon Risk — 53/100 (2026)
1 ZIP code · 3 water systems · Updated 2026-06-03
Monitoring data across Marriottsville 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 Marriottsville Compares
Data: EPA SDWIS Last verified: 2026-06-03
Key Facts for Marriottsville Residents
- Homes built before 1986: 34% — older plumbing may contain lead solder.
- Estimated remediation: $2,900 per household.
- CDC health risk index: 10.56.
Marriottsville's Water Providers
Residential water in Marriottsville, MD is supplied by 3 separate utilities — not one centralized authority. Each of those providers operates under its own service territory boundary, maintains its own distribution infrastructure, and files compliance documentation with the EPA on its own timeline. Federal data counts 3 water systems in the area, with these providers collectively accounting for the dominant share of household connections.
Overview
We track water quality and home safety data for 1 ZIP code in Marriottsville, Maryland (population ~5,786), covering 3 community water systems serving approximately 311,340 people region-wide.
No EPA violations recorded across any ZIP codes in Marriottsville — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Marriottsville: D (53/100)
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
Marriottsville water systems draw from: Surface water.
Lead & Copper
- Lead data: not yet available for Marriottsville
- 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 |
|---|---|---|---|
| 21104 | D | Howard County D.p.w. Distribution | 286,158 |
All ZIP Codes in Marriottsville
- 21104 [D]
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.
Marriottsville 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
Marriottsville Infrastructure Age
Housing age data helps assess potential lead pipe and infrastructure risks. Newer housing stock generally means lower plumbing-related contamination risk.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
Development in Marriottsville unfolded across multiple decades, and the median build year of 1995 reflects a housing inventory where eras of construction are genuinely mixed — including portions that predate the federal prohibition on lead solder in plumbing.
Most homes in Marriottsville were built after 1986, reducing the risk of lead contamination from plumbing. Older homes should still be tested.
Source: U.S. Census Bureau ACS B25034.
How Remediation Costs Compare in Marriottsville
Low proportionality — that's the Marriottsville picture when remediation costs are placed against typical home equity.
Remediation costs in Marriottsville are relatively low compared to home values. The $1,900–$4,100 estimated range is a small fraction of median property value. Home values are 54% above the Maryland average.
Marriottsville: 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.
Locally, 34% of Marriottsville homes carry interior plumbing from the era when lead solder was still permitted in new builds, and citywide monitoring approaches or crosses the EPA action benchmark. Households can find a draw-test kit and certified filtration through verified retailers.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Marriottsville: Flood History & Water Damage Risk
A moderate NFIP record for Marriottsville — 6 insurance claims paired with 100% of ZIP codes in FEMA flood zones — points to a flood history where water-quality pathways have likely been periodically relevant.
Marriottsville has a moderate flood history with 6 FEMA claims averaging $3,092 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>$2,900</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 Marriottsville
- 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 34% 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 Marriottsville, MD