Which water systems get a Tap Grade?

Only active Community Water Systems (CWS) — the utilities that serve the same residents year-round. Schools, campgrounds, and other transient or non-community systems are not graded, because this rubric is written for residential drinking water and would mislead if applied to them.

What does a missing grade or "no data" mean?

It means the system has no scored record for that measure in the EPA data we loaded — not that the water is confirmed safe. Absence of reported data is never counted as a clean result.

How current is the data?

The grade reflects the EPA Safe Drinking Water Act quarterly data (2026 Q2) downloaded 2026-07-16 and EPA UCMR5 occurrence data downloaded 2026-07-16. The five-year windows below are measured relative to that data vintage, not today’s calendar date.

I think a grade is wrong. How do I request a correction?

Email contact@tapgraded.com with the water system’s name or PWSID and what looks wrong. Because every deduction is reproducible from public EPA data, corrections are checked against the source records.

How the Tap Grade Works — Methodology

The rubric

Every system starts at 100 points. Points are then deducted:

1. Health-based violations (most recent 5 years)

−15 points for each unresolved health-based violation.
−8 points for each resolved health-based violation.
The total health-violation deduction is capped at −45 points, no matter how many there are.

A health-based violation is one flagged by EPA as health-based — a Maximum Contaminant Level (MCL), Maximum Residual Disinfectant Level (MRDL), or Treatment Technique (TT) violation. "Resolved" means the violation’s EPA status is Resolved or Archived; anything else (including Unaddressed or Addressed) is treated as still open for the −15 versus −8 split. Each violation is counted once (distinct violation), even though EPA’s data repeats it per enforcement action.

2. Monitoring & reporting violations (most recent 5 years)

−2 points for each monitoring or reporting violation.
This deduction is capped at −10 points in total.

These are the non-health-based violations — a system failed to test on schedule or to report a result on time. Violation categories other than health-based (that is, "Other") are counted in this monitoring/reporting bucket, not the health-based one. A monitoring or reporting lapse is a paperwork and oversight problem; it is weighted far more lightly than an actual exceedance of a health standard.

3. Lead (latest Lead & Copper Rule 90th-percentile sample)

−25 points if the latest 90th-percentile lead result is ≥ 15 ppb.
−15 points if it is ≥ 10 ppb (but under 15).
−8 points if it is ≥ 5 ppb (but under 10).
No deduction below 5 ppb.

The 90th-percentile value is the figure the Lead and Copper Rule is judged against — the level 90% of sampled taps fall below. Lead plausibility ceiling: a stored 90th-percentile reading above 1,000 ppb (about 67× the federal action level) is treated as a data-entry error — no credible reading — and scores no lead deduction, the same as a system that was never sampled. The raw figure is still shown on the system’s page with a data-quality caveat; only the grade ignores it.

4. PFAS ("forever chemicals," from UCMR5 occurrence data)

−20 points if any tested PFAS result is at or above its federal Maximum Contaminant Level (MCL).
−8 points if PFAS was detected at all, but every result was below its MCL.
No deduction if no PFAS was detected.

Only the five PFAS with a finalized federal MCL are scored against a limit: PFOA and PFOS (4 parts per trillion each), and PFHxS, PFNA, and GenX/HFPO-DA (10 parts per trillion each). See the contaminant pages for each limit and its regulatory status.

5. Currently unaddressed health violation

−10 additional points if the system has any health-based violation whose current EPA status is Unaddressed.

This is a flat penalty on top of the health-violation deduction above, and — unlike the 5-year windows — it reflects present-day status regardless of when the violation began.

From points to a letter

The remaining score (clamped to a 0–100 range) becomes a letter grade:

A worked example

Take the City of Georgetown, Texas (PWSID TX2460001), which serves about 191,600 people. From the EPA records loaded for this data vintage:

One unresolved health-based violation in the last 5 years (a Total Trihalomethanes MCL violation): −15.
Two monitoring/reporting violations in the last 5 years — one a monitoring/reporting violation, one an "Other"-category violation (a public-notice violation, counted here in the monitoring/reporting bucket): −2 × 2 = −4.
Lead: latest 90th-percentile result about 2.2 ppb, below the 5 ppb threshold: 0.
PFAS: PFOA detected at 4.9 ppt — at or above its 4 ppt MCL — so the at-or-above-MCL penalty applies: −20.
Unaddressed: that health-based violation’s current status is Unaddressed: −10.

100 − 15 − 4 − 0 − 20 − 10 = 51, which lands in the D band (50–64). Georgetown’s stored Tap Grade is a D — reproducing the computed score exactly.

Requesting a correction

Every deduction above is reproducible from public EPA records, so a grade can be checked against its sources. If you believe a Tap Grade is wrong, email contact@tapgraded.com with the system name or PWSID and what looks off, and we will re-check it against the source data.

How the Tap Grade works