US Water Grade publishes water quality reports for hundreds of U.S. cities. Because people use this information to make decisions about what they drink, we hold our content to a high standard of accuracy, transparency, and sourcing. This page explains exactly where our data comes from, how we turn it into a report, and how we keep it trustworthy.
In short: Our water quality data comes directly from official U.S. Environmental Protection Agency (EPA) databases. Every contaminant level, violation, and water-system detail you see on a city page is drawn from public federal records — not estimates, not user submissions, and not AI-invented numbers.
Where Our Data Comes From
The foundation of every report is government data. We do not generate, model, or guess contaminant levels. Our primary sources are:
- EPA Safe Drinking Water Information System (SDWIS): The federal database of public water systems, the contaminants they test for, measured levels, and the EPA Maximum Contaminant Levels (MCLs) those readings are compared against. This is the source of the contaminant tables on every city page.
- EPA Enforcement and Compliance History Online (ECHO): The federal record of violations, monitoring failures, and enforcement actions for each water system. This is the source of the compliance history we report.
- Consumer Confidence Reports (CCRs): The annual water quality reports that utilities are legally required to publish. We reference these for context and to corroborate SDWIS figures.
- EPA health guidance and MCL documentation: Used to explain what each contaminant is, why it matters, and how its measured level relates to federal safety limits.
We are an independent publisher. We have no affiliation with, and receive no funding from, any water utility, government agency, or filter manufacturer.
How We Turn Data Into a Report
Raw EPA data is technical and hard for most people to interpret. Our job is to translate it accurately. For each city we:
- Match the city to its water system(s) using the EPA Public Water System ID (PWSID), so the data shown belongs to the system that actually serves that community.
- Pull the measured contaminant levels and compare each one to its EPA MCL, expressing the result as a percentage of the legal limit so readers can see at a glance how close a contaminant is to the threshold.
- Calculate a water quality score (0–100) using a transparent, consistent model that weighs contaminant levels (50%), regulatory compliance history (30%), and infrastructure factors (20%). The full scoring breakdown is documented on our methodology page.
- Generate the written analysis directly from that city's own numbers — which contaminants are elevated versus safe, how the city compares to its state average and the national benchmark, and what those specific findings mean for residents. The analysis on a city page reflects that city's data, not a generic template.
Our Editorial Standards
- Accuracy over volume. We would rather publish fewer, genuinely useful reports than a flood of thin pages. Pages without a meaningful, data-backed finding are kept out of search indexes deliberately.
- No invented facts. Numbers come from EPA records. Where data is missing or unavailable for a system, we say so rather than filling the gap.
- Clear separation of data and recommendations. Contaminant readings and compliance records are facts. Filter suggestions are our independent opinion based on those facts, and any affiliate relationship is disclosed.
- Health information is general, not medical advice. We describe documented health effects of contaminants from established sources, and we always point readers to the EPA and qualified professionals for personal guidance.
Review, Updates, and Corrections
Water data changes as utilities test and report new results. We refresh our underlying EPA datasets periodically and re-derive scores and analysis from the updated figures. Each city report shows when it was last updated.
If you spot something that looks wrong — a contaminant level, a water system name, a violation record — we want to know. We treat corrections seriously and verify reported issues against the source EPA databases before making changes. You can reach us through our contact page.
Affiliate Disclosure
Some pages include links to water filters and home test kits. If you buy through those links we may earn a commission at no extra cost to you. These relationships never change the underlying EPA data we report, and product suggestions are based on the contaminants actually found in a given city's water. See our editorial guidelines for the full policy.
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