A draft screening index, not a medical verdict. Higher scores mean fewer benchmark-related findings in the reviewed records. An 80/100 does not mean “80% safe.” The method has not been independently validated.
We start at 100, subtract concern points, and cap the result at 95. Within each group, the highest reviewed reported result drives that group's deduction. Adding low readings cannot dilute a high one.
Draft point deductions by result ÷ comparison benchmark| Group | ≤ ¼ | ≤ ½ | ≤ 1× | ≤ 2× | > 2× |
|---|
| PFAS | 0 | 10 | 20 | 35 | 50 |
|---|
| Byproducts | 0 | 3 | 8 | 15 | 25 |
|---|
| Other inorganics | 0 | 3 | 8 | 20 | 30 |
|---|
Lead: 5 points for a detectable 90th percentile below or at the report action level; 25 above it. Disinfectants: no deduction at or below the annual residual limit; 15 above it. These point choices are product assumptions, not toxicological weights.
- A reported health-related violation during the covered year caps the draft score at 60, even when follow-up actions were completed.
- An individual lead tap above the action level caps the score at 75.
- A nondetect limit at or above a benchmark caps the score at 80. ND is never treated as zero.
- If PFOS, PFOA, byproducts, disinfectant residual, lead or other inorganic results lack usable data, we withhold the score. Individual FDEP chemical samples and monthly residuals do not replace report or annual statistics in the calculation.
Plant-specific results use their published statistic and date. A provider-wide score screens the highest reviewed result across its plants; it does not identify which plant serves your home. Different testing periods and sample statistics limit comparisons between providers.
We compare PFOA and PFOS with the 2024 EPA 4 ppt MCL benchmarks. Single samples are not compliance determinations. EPA's May 2026 changes were published as proposals; the source page explains their status. Lead uses the action level printed in the 2025 reports.
Hardness, pH and secondary taste/odor findings are separate. Not all contaminants or mixture effects are scored, and unbenchmarked PFAS detections remain visible. Current advisories and enforcement records have not been comprehensively checked.
EPA drinking water standards · EPA PFAS rule and proposals