Editorial Guidelines

Our commitment to accurate, transparent, and trustworthy water quality information for every American community.

Official Data Sources

All water quality data on US Water Grade originates from official U.S. government databases. We do not conduct our own water testing or generate independent measurements.

EPA Safe Drinking Water Information System (SDWIS)

Our primary data source. SDWIS is the official federal database containing water quality testing results, violation records, and compliance data for all 148,000+ public water systems serving Americans.

This database includes contaminant testing results, Maximum Contaminant Level (MCL) compliance, health-based violations, monitoring violations, enforcement actions, and system inventory information.

EPA ECHO (Enforcement and Compliance History Online)

Provides detailed compliance and enforcement data including formal enforcement actions, significant non-compliance status, and inspection history. We use ECHO to assess the regulatory track record of water systems.

Consumer Confidence Reports (CCRs)

Annual reports required by law from water utilities detail all contaminants detected and their concentrations relative to EPA limits. We cross-reference CCR data with SDWIS for comprehensive water quality profiles.

Report Interpretation Methodology

We translate complex EPA data into understandable grades and recommendations using a transparent, reproducible methodology:

EPA compliance record (up to −40, plus −20 if unresolved)

Every city starts at 100. Each health-based violation (MCL or treatment technique) in the last five years in EPA SDWIS costs 10 points, capped at 40; an unresolved health-based violation costs a further 20. Monitoring and reporting violations cost 1 point each, capped at 10.

Lead and PFAS (up to −25 and −26)

The system's latest Lead and Copper Rule 90th-percentile result (2020 or later) costs 25 points at or above the 15 ppb action level, 10 at 10 ppb, 3 at 5 ppb. PFOA or PFOS at or above 4 ppt in EPA's UCMR5 monitoring costs 10 points each; other PFAS detections 2 each, capped at 6.

Historical monitoring 2012–2019 (capped at −20)

EPA Six-Year Review samples for arsenic, nitrate, fluoride, chromium, uranium, radium and disinfection byproducts; exceedances and averages near the MCL cost 2–10 points per contaminant. No infrastructure, pipe-age or population factor is used — nothing in the score is estimated.

Grade Scale

Letter grades (A ≥90, B ≥80, C ≥70, D ≥60, F below 60) provide intuitive summaries, but we encourage users to review detailed contaminant data as individual contaminants may be of particular concern based on personal circumstances.

Data Update Process

We maintain our database to reflect current EPA data through a structured update process:

Quarterly Data Refresh: Our complete water quality database is refreshed quarterly to incorporate the latest EPA data releases, typically within 30 days of EPA publication.
Monthly Violation Updates: Violation records are updated monthly from EPA SDWIS and ECHO databases to ensure current compliance status.
Last Updated Display: Each city page displays the date of last data update so users can assess data currency.
Educational Content: Health guidance and educational content is reviewed semi-annually to ensure alignment with current EPA guidelines and scientific understanding.
Emergency Updates: Major contamination events or EPA advisories are reflected within 48 hours when possible.

Accuracy Standards

We maintain strict accuracy standards throughout our data pipeline:

No Data Modification: Contaminant readings and violation records are displayed as reported by the EPA. We do not adjust, estimate, or extrapolate values.
EPA Standards: All MCL comparisons use current EPA Maximum Contaminant Levels. When EPA updates standards, we implement changes in our next quarterly refresh.
Geographic Accuracy: Water system data is attributed to the correct service areas based on EPA system inventory records.
Periodic Audits: We regularly audit sample data against source EPA records to verify accuracy throughout our pipeline.
User Feedback: Reported discrepancies are investigated within 3 business days and corrected when verified.

Important Limitations

Users should understand the inherent limitations of water quality data:

Municipal vs. Home: Our data reflects water quality at treatment plants and distribution system testing points. Your home water may differ due to plumbing materials, pipe age, and building-specific factors.
Testing Gaps: Not all contaminants are tested regularly under federal law. Emerging contaminants (PFAS, microplastics, pharmaceuticals) may be under-reported or untested in some areas.
Regulatory Limits: EPA MCLs represent legally enforceable limits, but some MCLs have not been updated in decades. Health-based goals (MCLGs) are often lower than enforceable limits.
Data Latency: There can be delays between utility testing and EPA database publication. Our data may be several months old in some cases.
Private Wells: Our data covers public water systems only. Private well owners must test their own water.

Corrections Policy

We are committed to promptly correcting errors:

Data errors are corrected immediately upon verification, with notation for significant changes.
Users can report suspected errors through our contact page. We respond within 3 business days.
When EPA issues corrections or revised violation records, we incorporate changes in our next update cycle.

Editorial Independence

US Water Grade maintains complete editorial independence. Our water quality scores and data presentation are never influenced by advertising or affiliate relationships. We do not accept payment to feature, promote, or modify information about specific water systems, cities, or products.

Affiliate partnerships with water filtration companies are clearly disclosed. Product recommendations are based on NSF/ANSI certifications and contaminant removal capabilities, not commercial relationships.

Health Disclaimer

This website provides general information about water quality based on EPA data. It is not health advice and should not replace professional consultation.

Contact your local water utility for official water quality information. They are the authoritative source for your specific water supply and can provide your annual Consumer Confidence Report.

If you have health concerns related to water quality, particularly for vulnerable populations (infants, pregnant women, immunocompromised individuals), consult with a healthcare provider.

Questions about our methodology or data? Contact us or learn more on our About page.

Last updated: October 2026

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