Understanding Your Water Score
Your Water Score is a single 0–100 number that summarizes how clean your tap
water is, based on real EPA SDWIS violation data for the public water system
that serves your address. It starts at 100 and drops based on measured
contaminant levels, health-based violations on record, and water hardness — so a
lower score flags more issues to look into.
How the score is calculated
The score starts at 100 and is reduced based on measured contaminant levels
relative to health guidelines, the number of health-based violations on record,
and water hardness.
What the bands mean
- 0–40 (Poor): Multiple contaminants above health guidelines.
- 41–70 (Fair): Some elevated contaminants worth addressing.
- 71–100 (Good): Within guidelines on the measured contaminants.
Next step
See your city's data, then book a free 30-minute water test — no pitch.
Last updated June 3, 2026.
Common questions
- What is the Water Score?
- The Water Score is a single 0–100 number summarizing how clean your tap water is, based on EPA SDWIS violation data for the public water system serving your address. The score starts at 100 and is reduced for measured contaminant levels relative to health guidelines, health-based violations on record, and water hardness.
- How is the Water Score calculated?
- It begins at 100 and is lowered based on three inputs from EPA records: measured contaminant levels relative to federal health guidelines, the number of health-based violations on file in EPA SDWIS, and local water hardness. A higher score means fewer issues on record for the measured contaminants.
- What do the Water Score bands mean?
- 0–40 (Poor) means multiple contaminants above health guidelines. 41–70 (Fair) means some elevated contaminants worth addressing. 71–100 (Good) means the system is within guidelines on the measured contaminants. The score reflects the public system on record, not your home's plumbing, so an in-home test is still the only way to confirm what's at your tap.