Home Safety Score
Get a coverage-qualified safety grade from four required evidence components across three domains.
- Four required inputs: water compliance, PFAS, radon, and annual AQI
- Contextual risk signals showing which issues may deserve attention
- Prioritized action plan with specific steps to reduce your household risk
Measured Score Components
Broader Home Safety Profile
These registry verticals remain visible for whole-home screening but do not change model 4.0.0. Review their dedicated tools and property-level sources separately.
How Your Score Is Calculated
Model 4.0.0 uses four required evidence components across three equally weighted domains. A missing component makes the score and grade unavailable.
| Category | Domain | What It Measures |
|---|---|---|
| Water Compliance | Drinking water (1 of 2) | Accepted EPA SDWA lifecycle counts: current addressed and unaddressed records at full weight, resolved records at 0.25x, and archived records at zero |
| PFAS MCL Screen | Drinking water (1 of 2) | Accepted UCMR5 testing; untested evidence remains unavailable |
| Radon | Indoor environment | EPA radon zone classification (Zone 1 = highest risk, >4 pCi/L) |
| Annual AQI | Outdoor environment | EPA annual county AQI with at least 90 reporting days |
The broader Home Safety Profile reports 17 or more registry verticals separately. Context verticals do not change model 4.0.0.
How Grades Work
| Grade | Score | What It Means |
|---|---|---|
| A | 85-100 | Excellent - low risk across most measured components |
| B | 70-84 | Good - some measured risks may need review |
| C | 55-69 | Fair - notable measured risks deserve attention |
| D | 40-54 | Below average - multiple measured risks are elevated |
| F | 0-39 | Poor - significant measured risks need attention |
How New Vertical Categories Are Added
The original 17 vertical IDs are an immutable historical baseline, not a maximum. A new vertical is appended first as a candidate, context, or absent category with source contracts, blocking gates, evidence debt, and lineage. It can enter a future score only in a new model version after those gates pass. A replacement source within one vertical must form an explicit linear supersession chain; model 4.0.0 never changes silently.
Frequently Asked Questions
What is a good Home Safety Score?
Grade A is 85-100, B is 70-84, C is 55-69, D is 40-54, and F is 0-39. A grade is published only with complete coverage.
How often is the data updated?
The federal sources publish on different schedules. Each report identifies the available source vintage; a page publication date does not mean every upstream source changed that day.
Can I improve my Home Safety Score?
The score reflects area-level evidence, not an individual home. Appropriate testing and mitigation can address a component even when the area-level source record remains unchanged.
How is the score different from individual tools?
The Home Safety Score uses four components. Individual tools and contextual signal cards cover additional topics in more detail without changing the score.
Can realtors and homebuyers use this for due diligence?
Yes. The score can support an initial area-level screen of its four accepted inputs. Separate contextual signals cover other topics. Neither replaces a property inspection or required disclosure.
Data Sources & Methodology
Data Sources
- EPA SDWIS and EPA ECHO — Water-system identity plus accepted SDWA violation lifecycle evidence; current records have full weight, resolved records 0.25 weight, and archived records zero weight
- EPA UCMR5 — Published PFAS monitoring with an accepted current-MCL screen
- EPA Radon Zone Map — County-level radon zone classifications (Zone 1-3)
- EPA AirData — Annual county AQI with explicit monitoring-day coverage
- Separate contextual sources — CDC, USGS, Census, and other federal indicators displayed separately without changing the score
Methodology
Model 4.0.0 averages SDWIS and accepted ECHO SDWA lifecycle-based water compliance with PFAS inside drinking water, then averages drinking water, radon, and annual AQI as three equal domains. All four inputs are required. Grades are A 85-100, B 70-84, C 55-69, D 40-54, and F 0-39.