Is Your Tap Water Safe to Drink?

Every city on US Water Grade receives a letter grade from A to F, derived from a numerical score on a 0-to-100 scale. These grades are designed to give you an at-a-glance understanding of how your city's tap water compares to both federal safety standards and health-based guidelines. Here is what each grade means and what actions you might consider based on your city's rating.

Grade A (90-100): Excellent water quality. All tested contaminants are well below EPA Maximum Contaminant Levels, and the water system has a clean compliance record with no recent violations. Cities with Grade A water typically have modern treatment facilities, well-maintained infrastructure, and clean source water. While no public water supply is completely contaminant-free, Grade A cities have the lowest detected levels across the board. A basic carbon filter for taste improvement is optional but not a health necessity for most residents.

Grade B (80-89): Good water quality. Contaminant levels are below EPA limits, though some may be approaching the threshold or exceed stricter EWG health guidelines. The water system may have minor compliance issues that have been resolved. Grade B water is generally safe for most people, but individuals with compromised immune systems, pregnant women, or families with infants may want to consider a carbon or pitcher filter as an added precaution, particularly if specific contaminants of concern are flagged in the report.

Grade C (70-79): Average water quality. Some contaminants are detected at levels that, while still within EPA legal limits, exceed health-based guidelines from organizations like the EWG. The system may have a history of minor violations or monitoring gaps. For Grade C cities, we recommend reviewing the specific contaminants detected in your report and considering a filter matched to those concerns. Common issues at this level include elevated disinfection byproducts, moderate nitrate levels, or trace amounts of industrial chemicals.

Grade D (60-69): Below average water quality. One or more contaminants may be approaching or occasionally exceeding EPA limits, and the system likely has a record of violations. Residents in Grade D cities should take proactive steps to protect their drinking water, including installing a certified water filter appropriate for the specific contaminants detected. We recommend reviewing the detailed contaminant breakdown in your city's report and considering a reverse osmosis system if multiple contaminants are elevated.

Grade F (0-59): Poor water quality requiring immediate attention. Contaminant levels may exceed EPA limits, the system may have active or unresolved violations, and there are significant concerns about long-term exposure. Residents in Grade F areas should strongly consider using a high-quality water filter such as a reverse osmosis system, request their utility's most recent Consumer Confidence Report, and consider independent home water testing to understand what is coming out of their specific tap. Boil water advisories or do-not-drink orders may be in effect for the most severe cases.