WaterQ

Know What's in Your Water. Know What to Do About It.

Look up your city's EPA water quality data, then get matched to the specific NSF-certified filter that actually removes what's in your tap — not generic advice.

Not sure what filter you need? See our contaminant-based guide →
50
States
11,696
Cities
187
Systems
86
Avg Score

Top States

View All →
1
Washington
480 systems
95 A
2
North Dakota
92 systems
93 A
3
Delaware
62 systems
91 A
4
Maryland
165 systems
91 A
5
Nebraska
140 systems
91 A
6
South Dakota
115 systems
91 A
7
California
1,081 systems
90 A
8
Michigan
584 systems
90 A
9
Minnesota
362 systems
90 A
10
South Carolina
249 systems
89 B

Top Cities

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1
Aberdeen
ID ·
100 A
2
Adams Center
NY ·
100 A
3
Addison
AL ·
100 A
4
Addison
TX ·
100 A
5
Adkins
TX ·
100 A
6
Adrian
MI ·
100 A
7
Aitkin
MN ·
100 A
8
Albion
NY ·
100 A
9
Alexandria Bay
NY ·
100 A
10
Algoma
WI ·
100 A
Real-Time Compliance

Recent Violations

Monitoring daily EPA reporting to ensure your information is always current.

Treatment Technique Violation
PWSID: NH1361011
Date Detected
2025-10-19
minor unresolved
Treatment Technique Violation
PWSID: TX0710001
Date Detected
2025-10-09
critical resolved
Inorganic Chemicals Violation
PWSID: MA3349000
Date Detected
2025-09-28
critical resolved
Maximum Residual Disinfectant Level
PWSID: NC0392011
Date Detected
2025-08-09
critical resolved
Maximum Contaminant Level Violation
PWSID: LA1170001
Date Detected
2025-08-07
major pending

Popular Comparisons

Compare tap water quality between major US cities side-by-side.

Valhalla vs Houston
NY vs TX
Valhalla vs Los Angeles
NY vs CA
Valhalla vs San Jose
NY vs CA
Valhalla vs Chicago
NY vs IL
Valhalla vs Chelsea
NY vs MA
Houston vs Los Angeles
TX vs CA
Houston vs San Jose
TX vs CA
Houston vs Chicago
TX vs IL
Houston vs Chelsea
TX vs MA
Los Angeles vs San Jose
CA vs CA
Los Angeles vs Chicago
CA vs IL
Los Angeles vs Chelsea
CA vs MA

Trending Cities

Popular locations this week based on search intent and water quality reports.

Fairbanks, AK Fresno, CA San Jose, CA Sacramento, CA San Francisco, CA Houston, TX Fargo, ND

Expert Guides

Research Library →
Trending Local Guide

Do You Need a Water Filter in Fairbanks?

An expert breakdown of Fairbanks water quality, local contaminants, and whether a filtration system is truly necessary for your home.

View Local Guide →
Educational

How to Read a Water Report Step by Step

Learn what MCL, detected levels, and violation terms mean so you can interpret data confidently.

Read Manual →
Health Alert

Lead in City Water: How to Check Risk

Use city comparison data and contaminant pages to quickly assess lead exposure risk.

Read Manual →
About WaterQ

Water Data That Ends in an Action, Not Just a Number

WaterQ pulls drinking water quality data from the U.S. EPA's Safe Drinking Water Information System (SDWIS) for over 187 public water systems across all 50 states. But a score by itself doesn't tell you what to do — so every report is built to end in one of three concrete next steps: a specific NSF-certified filter recommendation, a water-testing referral if you're on a private well, or a free alert subscription if you'd rather just be notified when something changes.

Our water quality scores combine contaminant detection levels, EPA Maximum Contaminant Level (MCL) compliance records, and violation histories into a single 0–100 score with a letter grade. All data is sourced directly from official EPA records and updated quarterly — we do not extrapolate or estimate. Read our full methodology →

Data Source
EPA SDWIS
Safe Drinking Water Information System
Updated
Quarterly
From official EPA release cycle
Coverage
All 50 States
187 water systems

Frequently Asked Questions

How safe is my tap water? +
WaterQ scores each water system using EPA compliance records. Search your city to see a 0–100 quality score and letter grade. Systems with recent health-based violations are flagged for your attention.
Where does WaterQ data come from? +
All data is sourced from the U.S. EPA Safe Drinking Water Information System (SDWIS) — the official federal database where public water utilities report compliance results. We do not estimate or extrapolate.
How often is WaterQ data updated? +
Data is updated quarterly when the EPA releases new SDWIS records. Each system page shows the data timestamp so you always know how current the information is.
What is an MCL violation? +
An MCL (Maximum Contaminant Level) violation means a detected contaminant exceeded the federal safety threshold set by the EPA. Health-based violations require immediate public notification by the water utility.
Do I need a water filter? +
It depends on your local water quality score and contaminant profile. WaterQ's city and system pages show detected contaminants and their levels. Our expert guides help you decide if filtration is worthwhile for your area.

Pure Data.
Clear Next Step.

Sourced directly from the EPA Safe Drinking Water Information System.

Check Your Water Find Your Filter