Water in Delaware.
Delaware sits at the intersection of agricultural Sussex County and the industrial I-95 corridor. PFAS, nitrate, and chemicals from legacy industry all appear in state monitoring data.
How Delaware regulates drinking water.
Federal SDWA primacy. State maintains its own PFAS response program; New Castle County sites are under Superfund-led remediation.
Delaware's water history, in order.
The contamination events, regulatory shifts, and major settlements that define how this state thinks about drinking water today.
- 2014
PFAS contamination documented at Dover Air Force Base.
- 2020
Statewide nitrate-and-PFAS sampling expanded in Sussex County agricultural zone.
The actual water you drink.
The physical rivers, aquifers, lakes, and reservoirs that feed Delaware's public water systems. Source quality is the foundation of tap quality — and where the long-term protection fights happen.
- riverBrandywine + Christina Rivers
Wilmington area.
- aquiferCohansey-Mount Laurel Aquifer
Sussex County agricultural region.
- aquiferColumbia Aquifer
Coastal Delaware.
Source-water mix
~60% groundwater, ~40% surface water
Major cities served
Wilmington · Dover · Newark
Who actually serves the water.
The largest public water systems in Delaware by population served. Click your ZIP after to see the full live EWG report for your specific utility.
- Wilmington Department of Public WorksWilmington70Kserved
- Artesian Water CompanyMulti-county300Kserved
- Tidewater UtilitiesSussex County110Kserved
Where the contamination comes from.
Every state has a different industrial fingerprint. The industries below are the dominant historical and active contamination sources in Delaware's drinking water systems.
Dover Air Force Base PFAS contamination is the most-documented military site in DE. DuPont's legacy Chambers Works (across the Delaware River in NJ) affects Delaware River shoreline systems. Poultry operations in Sussex County drive nitrate exposure.
What state data flags most consistently.
Drawn from EPA SDWIS sampling records, EWG state summaries, and regional regulatory action over the past five years. Read the full deep dive on each.
PFAS (Forever Chemicals)
A class of ~15,000 synthetic chemicals that don't break down. Now regulated for the first time.
Nitrate
Fertilizer and animal waste runoff. Acutely dangerous for infants under 6 months.
Trihalomethanes (TTHMs)
Byproducts of chlorinating water. Linked to bladder cancer at chronic exposure.
Risk isn't evenly distributed.
Sussex County agricultural communities face the highest combined nitrate-and-PFAS exposure. Dover Air Force Base neighborhoods face documented PFAS.
~17% on private wells, concentrated in Sussex County agricultural areas.
What's coming for Delaware's water.
Saltwater intrusion threatens Sussex County aquifers — among the most-vulnerable in the mid-Atlantic. Sea-level rise on the Delaware Bay coastline displaces shallow wellfields. Flooding events increase agricultural runoff into surface intakes.
Voluntary statewide
Delaware Division of Public Health provides voluntary screening assistance.
Five questions for your next Consumer Confidence Report.
Your utility is required to send you a Consumer Confidence Report annually. Most are dense and procedural. These are the questions worth following up on for Delaware specifically.
- 1
Is my well at risk of saltwater intrusion if I'm in Sussex County?
- 2
Has Dover-area PFAS sampling reached my neighborhood?
- 3
What is my utility's nitrate running average?
Most state regulators allow public records requests for the underlying lab reports behind your CCR — your utility should be able to provide them on request.
Reverse osmosis (NSF/ANSI 58) is the most effective home solution for the Delaware nitrate + PFAS combination.
We don't recommend brands — the NSF/ANSI certification number matters more than the name on the box.
This is the state. Your address is the answer.
State-level patterns don't tell you about your specific tap. Run your ZIP for the live EWG contaminant report on your utility — or build a personalized Water File for your household.
Source-water mix, utility counts, lead-service-line estimates, and private-well shares are approximate, drawn from EPA SDWIS public data and state primacy-agency summaries. Contaminant rankings reflect EWG state-level monitoring data and regional regulatory action — they are not exhaustive. Timeline events are publicly documented. See methodology for the full sourcing. Search EPA SDWIS for Delaware