Untested Private Well Water

Private well, never tested.

36High burden · out of 100

Cleaner swapAnnual testing + a targeted filter

How this score is built

100Start
72.4Chemical hazard 6 × 4.6−27.6
48.6Everyday exposure 7 × 3.4−23.8
36Persistence 5 × 2.6−13, then rounded to 36
HighThe band36 sits in 20–39.

What each input rests on

The three ratings behind the score, and the studies each rests on
Input	Rating	Evidence
Chemical hazard	6/10	In a New England case-control study (1,213 cases), people with the highest cumulative arsenic exposure from drinking water had about twice the bladder-cancer risk of the lowest quartile (odds ratio 2.24). Elevated Bladder Cancer in Northern New England: The Role of Drinking Water and Arsenic · J Natl Cancer Inst 2016 DOI 10.1093/jnci/djw099 · PMID 27140955 · Abstract, Results · read 2026-10-02
Everyday exposure	7/10	About 44.1 million people in the US use domestic wells; an estimated 2.1 million (95% CI 1.5 to 2.9 million) use wells with predicted arsenic above 10 μg/L. Estimating the High-Arsenic Domestic-Well Population in the Conterminous United States · Environ Sci Technol 2017 DOI 10.1021/acs.est.7b02881 · PMID 29043784 · Abstract · read 2026-10-02
Persistence	5/10	In a three-decade tracer experiment, 12–15% of fertilizer nitrogen still resided in soil after more than a quarter century, and nitrate export toward water is predicted to continue for at least five more decades. Long-term fate of nitrate fertilizer in agricultural soils · Proc Natl Acad Sci U S A 2013 DOI 10.1073/pnas.1305372110 · PMID 24145428 · Abstract · read 2026-10-02

Ratings are editorial. A study listed here supports the rating; it did not compute it. How the index is built

What this means for you

The chemical-hazard rating is what drives the score down. Wells aren't covered by public water rules. Arsenic, nitrates, bacteria and agricultural runoff are all possible and invisible without a test.

Evidence strength: moderate

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Lower-exposure choices

Reverse-Osmosis Filtered WaterMinimal · Water

Carbon-Filter Pitcher WaterLow · Water

All 8 water entries, highest burden first →