About SafeNest
How Grades Work
SafeNest evaluates the environmental health of US ZIP codes by analyzing publicly available EPA data. Each ZIP code receives grades across multiple categories — currently Water Quality and Toxic Sites — which are combined into a weighted overall grade. Scores range from 0.00 to 4.00, mapped to letter grades from F (Critical) to A (Excellent).
The overall grade is a weighted average of all categories that have available data. If a category lacks sufficient data, it is excluded from the overall calculation rather than penalizing the ZIP code.
Scoring Scale
| Grade | Score Range | Meaning |
|---|---|---|
| A | 3.50 - 4.00 | Excellent |
| B | 2.50 - 3.49 | Good |
| C | 1.50 - 2.49 | Fair |
| D | 0.50 - 1.49 | Poor |
| F | 0.00 - 0.49 | Critical |
Water Quality Methodology
Water quality scores start at 4.0 (perfect) and deduct points based on violations and enforcement actions reported to the EPA’s Safe Drinking Water Information System (SDWIS):
- Health-based violations (past 5 years): -0.5 per violation. These indicate contaminant levels that may pose health risks.
- Maximum Contaminant Level (MCL) exceedances (past year): -1.0 per exceedance. These are the most serious violations.
- Monitoring violations: -0.1 per violation. These indicate the utility failed to test as required.
- Enforcement actions: -0.3 per action. These indicate the EPA or state took formal action against the utility.
Toxic Sites Methodology
Toxic site scores also start at 4.0 and deduct points based on the proximity and severity of hazardous facilities:
- TRI facilities within 5 miles: -0.1 per facility. Facilities that report toxic chemical releases to the EPA.
- Total chemical releases: -0.5 per 50,000 lbs released. Higher volumes pose greater exposure risk.
- Carcinogen releases: -0.5 if any facility nearby releases known carcinogens.
- Superfund NPL sites within 2 miles: -2.0. These are the most severely contaminated sites in the country.
- Superfund NPL sites within 5 miles: -1.0 (if none within 2 miles).
- Non-NPL Superfund sites within 5 miles: -0.3 per site.
- RCRA violations nearby: -0.2 per violation. Hazardous waste handling violations.
Data Sources
| Source | Description |
|---|---|
| EPA SDWIS Safe Drinking Water Information System | Tracks drinking water violations, enforcement actions, and water system information for public water systems across the United States. |
| EPA TRI Toxics Release Inventory | Annual reporting of toxic chemical releases and waste management activities by industrial facilities. Covers over 650 chemicals. |
| EPA Superfund / NPL National Priorities List | Identifies the most contaminated sites in the country that pose the greatest risk to human health and the environment. |
| EPA RCRA Resource Conservation and Recovery Act | Tracks hazardous waste generators, transporters, and treatment, storage, and disposal facilities, including compliance violations. |
Insufficient Data
Some ZIP codes may show an “Insufficient Data” badge for one or more categories. This occurs when we cannot find matching EPA records for that ZIP code — for example, if the area is served by a private well rather than a public water system, or if no TRI-reporting facilities exist nearby.
When a category lacks data, it is excluded from the overall grade calculation. A ZIP code with only one category graded will show its overall grade based solely on that category. If no categories have data, no overall grade is assigned.
Disclaimer
SafeNest is an informational tool and does not constitute professional environmental, health, or real estate advice. Grades are derived from publicly available EPA data and simplified scoring models. Actual environmental conditions can vary significantly within a ZIP code. Always consult qualified professionals and conduct site-specific assessments before making decisions about where to live, work, or invest. Data may not reflect the most recent conditions, and the absence of data does not guarantee the absence of environmental hazards.