Douglas County, Colorado
13 ZIP codes · Avg score 65/100 · Grade C · Updated 2026-06-03
The systems supplying Douglas County's 13 ZIP codes vary in performance — most meet minimum standards, but violations in select areas are on record.
How Douglas County Compares
How Douglas County Compares
Douglas County scores 5 points above the Colorado state average (60/100) and 3 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Douglas County, Colorado
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 9.4 (asthma 10.5%, diabetes 6.8%)
Estimated additional annual cost per homeowner: $753, driven primarily by flood
Infrastructure: 0.256% avg pipe failure probability
21.1% of homes built before 1978 (lead paint era)
Violation History (2022–2023)
→ Stable trendEPA violation counts by year across Douglas County water systems. Health-based shown in red, total in blue.
Peak year: 2023 with 4 violations. Past 5 years: 5 total (5 health-based).
Source: EPA SDWIS historical violations. Data may lag 6–12 months for the most recent year.
County Health Indicators vs National Average
Black markers indicate national averages. Source: CDC PLACES, Census ACS.
Infrastructure Overview
Sources: Census ACS (housing age), EPA SDWIS (infrastructure risk model), state bridge inspection data.
Compound Risk Breakdown
Estimated additional annual cost per homeowner: $753
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
123,875 housing units in Douglas County
Source: U.S. Census Bureau ACS B25034 (Year Structure Built).
Water Safety Affordability
How much it costs to fix water issues relative to home values in Douglas County
Remediation costs are relatively manageable for most homeowners in Douglas County, representing a small fraction of property value.
Remediation includes water filtration, lead abatement, radon mitigation, and flood protection where applicable. Source: Census ACS, EPA SDWIS.
Health Outcomes vs National Average
CDC PLACES data for Douglas County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water Systems with Most Violations
Top 5 systems in Douglas County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Castle Rock Town of | 106,822 | 49 |
| 2 | Perry Park Water Supply District | 3,890 | 30 |
| 3 | Consolidated Bell Mtn Ranch Md | 1,000 | 29 |
| 4 | Parker Water Supply District | 75,949 | 18 |
| 5 | Pinery Wwd | 12,901 | 18 |
23 total water systems serve Douglas County.
All ZIP Codes in Douglas County
13 ZIP codes tracked in Douglas County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 80125 | Littleton | 70 | B | 0 | $708K |
| 2 | 80126 | Littleton | 70 | B | 0 | $714K |
| 3 | 80129 | Littleton | 70 | B | 0 | $643K |
| 4 | 80130 | Littleton | 70 | B | 0 | $653K |
| 5 | 80104 | Castle Rock | 68 | C | 4 | $587K |
| 6 | 80108 | Castle Rock | 68 | C | 4 | $814K |
| 7 | 80109 | Castle Rock | 68 | C | 4 | $649K |
| 8 | 80163 | Littleton | 66 | C | 0 | — |
| 9 | 80135 | Sedalia | 64 | C | 13 (1 health) | $895K |
| 10 | 80138 | Parker | 64 | C | 7 | $680K |
| 11 | 80118 | Larkspur | 60 | C | 17 (4 health) | $827K |
| 12 | 80134 | Parker | 59 | C | 7 | $643K |
| 13 | 80116 | Franktown | 53 | D | 0 | $905K |
Recommended Buyer Guides for Douglas County
Methodologically, the recommendation order reflects severity in the federal record: contaminants flagged in EPA detection records for this county outrank generic water concerns, FEMA-confirmed hazard ratings shift emergency-related categories upward, and CDC lead-exposure markers govern when lead-test kits and certified filters appear at the top of the list.
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
- Best Radon Test Kits — EPA Radon Zone 1 (highest risk) dominant in county
- Best Sump Pumps — Flood is the top compound risk factor
- Best Mold Test Kits — Flood-driven moisture and mold risk
Deep Dive Reports
Detailed analysis for Douglas County, Colorado
Overview
Douglas County in Colorado covers 13 ZIP codes with an average Home Safety Score of C (65/100).
7 of 13 ZIP codes have recorded EPA violations. 5 health-based violations have been documented.
← Back to Colorado water quality report
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Home values: U.S. Census Bureau ACS (median estimates by ZCTA)
Updated daily.