Though many humans don't suffer directly from water quality issues within the state, the natural world and all of the services that it provides are greatly impacted. In a report done by the Environmental Integrity Project, 97% of Delaware's waterways were deemed to be polluted.

Delaware faces several significant water quality challenges in 2026, primarily related to "forever chemicals" (PFAS), legacy industrial pollution, and agricultural runoff. Recent state-wide testing has shown that many public water systems and private wells contain levels of PFAS—substances used in firefighting foam and non-stick products—that exceed new, stricter federal safety standards. Additionally, the state's shallow water table makes it susceptible to contamination from nitrates used in large-scale poultry farming and septic systems, particularly in southern Delaware. In urban areas like Wilmington, aging infrastructure and lead service lines remain a concern. To address these issues, the Delaware Department of Natural Resources and Environmental Control (DNREC) has launched a multi-million dollar "Clean Water for Delaware" initiative focused on upgrading treatment plants and providing grants for private well filtration. While the municipal tap water in major towns is rigorously monitored and generally safe to drink, the presence of these emerging contaminants means that many residents still choose to use home filtration systems or bottled water as an added precaution for their long-term health and peace of mind.