Mountlake Terrace, WA: 2 Violations — 85/100 (2026)
1 ZIP code · 2 water systems · Updated 2026-06-03
Water systems serving Mountlake Terrace hold a strong EPA compliance record — the city places among the better-performing areas in WA with few health-based violations on file.
How Mountlake Terrace Compares
Data: EPA SDWIS Last verified: 2026-06-03
Mountlake Terrace Water: The Quick Version
- Your city's water systems recorded 2 violations in the past 5 years.
- Homes built before 1986: 75% — older plumbing may contain lead solder.
- Estimated remediation: $1,200 per household.
- CDC health risk index: 10.74.
Water Systems Serving Mountlake Terrace
Water supply in Mountlake Terrace, WA follows a divided structure: 2 utilities account for the largest share of residential service out of 2 total systems, each managing its own distribution network and EPA reporting. Because these systems operate independently, rate decisions and compliance outcomes are determined separately.
Overview
We track water quality and home safety data for 1 ZIP code in Mountlake Terrace, Washington (population ~21,417), covering 2 community water systems serving approximately 226,402 people region-wide.
1 of 1 ZIP code (100%) have recorded EPA violations. All violations are monitoring/reporting type.
Home Safety Score
Average Home Safety Score for Mountlake Terrace: A (85/100)
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
Mountlake Terrace water systems draw from: Surface water.
Lead & Copper
- Lead data: not yet available for Mountlake Terrace
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 3 (Low Risk)
Top Contaminants
| Contaminant | Category | Violations | ZIPs Affected |
|---|---|---|---|
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 2 | 1 |
| Surface Water Treatment Rule | Treatment Technique | 2 | 1 |
Areas with Most Violations
| ZIP Code | Safety Score | Violations | Health-Based | System |
|---|---|---|---|---|
| 98043 | A | 2 | 0 | City of Mountlake Terrace |
All ZIP Codes in Mountlake Terrace
- 98043 [A] — 2 violations
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 Mountlake Terrace
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
Key Contaminants Detected in Mountlake Terrace
Based on EPA violation records. Check your ZIP code report for system-specific contaminant data.
How Old Is Mountlake Terrace's Housing Stock?
With 75% 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
Decades of residential development in Mountlake Terrace took place before the two main regulatory milestones that reduced plumbing-era lead risk: the phase-out of lead pipes before 1970, and the federal ban on lead solder in 1986. With a median build year of 1979, the housing stock here is anchored in that earlier period. The distinction between pre-1970 and 1970-to-1986 construction matters: the oldest homes may have lead pipes in the service line and lead solder in the copper joints, while the 1970-to-1986 tier still carries the solder risk even after lead pipes became less common. Together, these two risk layers affect a majority of the residential properties in the city — a fact the aggregate water quality data doesn't directly reveal.
Over half of homes in Mountlake Terrace 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.
Mountlake Terrace: Remediation Cost in Perspective
In Mountlake Terrace, 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 Mountlake Terrace are relatively low compared to home values. The $800–$1,800 estimated range is a small fraction of median property value. Home values are 30% above the Washington average.
Protecting Children from Lead in Mountlake Terrace
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.
Households with kids in the home — for whom CDC guidance places particular weight on minimizing exposure — face a specific local picture in Mountlake Terrace. 75% of homes here come from the pre-rule era, and aggregate utility samples either approach or cross 0.015 mg/L. A baseline draw-test kit and certified lead-removal filtration are available via retailer networks for households confirming conditions at a specific tap.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Climate-Related Water Risk for Mountlake Terrace
A moderate NFIP record for Mountlake Terrace — 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.
Mountlake Terrace has a moderate flood history with 6 FEMA claims averaging $8,908 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>$1,200</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 Mountlake Terrace, WA