Delaware Tap Water Quality Report

Drinking water quality in Delaware is widely considered to be above the national average, maintaining an impressive composite safety score of 80.6/100 across its 97 monitored ZIP codes. Based on the latest records from the EPA's Safe Drinking Water Information System (SDWIS), a remarkable 31% of ZIP codes in Delaware have earned an "A" grade. This reflects strong regulatory compliance, robust municipal water treatment infrastructure, and generally low levels of detected health-based contaminants across most communities in the state.

Over the past 5 years, water utilities in Delaware have recorded a total of 155 violations, of which 14 were strictly health-based. While administrative and reporting violations are common nationwide, health-based violations mean that certain contaminants exceeded the EPA's Maximum Contaminant Levels (MCLs) at some point. Delaware Division of Public Health, which acts as the primary regulatory authority in the state, typically works closely with these utilities to issue boil water advisories or mandate infrastructure upgrades when these limits are breached.

Fortunately, the risk of widespread lead exposure in Delaware's municipal water is relatively low compared to other states, with only 24.7% of ZIP codes falling into the High or Very High risk categories. However, because lead primarily enters drinking water through the corrosion of individual home plumbing rather than the main municipal supply, residents living in homes built prior to 1986 should still exercise caution. Using a standard carbon block filter and running the tap for 30 seconds each morning remains a recommended best practice for all households.