WaterQ

Delaware Tap Water Quality Rankings 2026: 3rd in Nation | WaterQ

Alex Carter
By Alex Carter
Water Quality Researcher ยท Published 2026-06-23

Delaware ranks 3rd out of 50 states for its drinking water quality, earning an overall grade of A with an average score of 91. The state manages 62 water systems serving a population of 993,617 residents. However, despite the high state-level rank, there were 1,033 recorded water system violations across the state during the reporting period.

Key Findings for Delaware

Reviewing EPA SDWIS data for 2026, here's what defines Delaware's water quality landscape:

  • The Mid-Atlantic coastal plain geography of Delaware makes shallow groundwater aquifers vulnerable to agricultural runoff, which can elevate nitrate levels.
  • Industrial and chemical legacies near the Wilmington area present potential risks for industrial contaminants like PFAS in nearby water systems.
  • Older municipal infrastructure in established urban areas can pose risks of lead leaching from aging service lines and household plumbing components.

Most Common Contaminants in Delaware

Here's what Delaware residents should know about the contaminants most relevant to their water:

Nitrate

Often entering groundwater from fertilizer use and agricultural runoff, particularly in the agricultural regions of the coastal plain.

PFAS

Per- and polyfluoroalkyl substances are associated with historic industrial and chemical manufacturing legacies in urbanized areas like near Wilmington.

Lead

Typically introduced into drinking water through the corrosion of older service lines and household plumbing materials.

Delaware's Best and Worst Cities for Water Quality

For detailed water quality reports and specific testing results in your municipality, please consult the local water system data provided on our state directory page. Explore the full breakdown on our Delaware water systems page.

What Delaware Residents Should Do

Given Delaware's 3rd place ranking, here's what matters most for residents:

  1. Search for your local water system's annual Consumer Confidence Report (CCR) to review its specific compliance history.
  2. If your home relies on a private well, schedule regular testing since wells are not monitored by public water utilities.
  3. Identify if your home has lead service lines or lead plumbing and use an appropriate NSF-certified filter if lead is suspected.
  4. Verify your water supplier's EPA violation history to stay informed about recent compliance issues.

Frequently Asked Questions

How does Delaware water quality compare to other states?

Delaware performs exceptionally well relative to other states, ranking 3rd out of 50 nationwide. The state achieved an average score of 91, resulting in an overall grade of A. While its water systems are highly rated on average, residents should still review localized data for individual system violations.

What are the most common contaminants in Delaware tap water?

Common risks in Delaware are primarily associated with the state's geography and history, including nitrate from agricultural activities on the coastal plain and PFAS from the industrial legacy near Wilmington. Additionally, lead remains a potential concern for homes with aging plumbing and service lines.

Is it safe to drink tap water in Delaware?

With an overall grade of A and a national rank of 3, Delaware's public tap water generally meets high safety standards. However, local violations do occur, and residents using private wells or older home plumbing should perform targeted testing to ensure safety.

Source: EPA SDWIS 2026 Compliance Data and WaterQ National Database. For more information on our ranking process, visit our state rankings page.