Nitrate In Drinking Water In Delaware
What residents of Delaware need to know about nitrate in drinking water — including how it enters water, which utilities have documented violations, and what steps to take.
Source: EPA SDWIS, Delaware Division of Public Health (DDPH), CDC · Last reviewed: 2025-01-01
Quick Answer
Is nitrate in drinking water a real concern in Delaware?
Yes — Delaware is one of the most intensively farmed states by land area, with a very high concentration of poultry operations. Nitrate contamination in Delaware's shallow coastal plain aquifer is a documented public health concern.
Is this mostly a public-water issue, a private-well issue, or both?
Both private well users and some small public systems in Delaware's agricultural counties; Sussex County in southern Delaware has the highest poultry density and documented nitrate concerns.
What is the main reason residents should care?
Delaware has one of the highest concentrations of chicken broiler operations per square mile of any state. Poultry litter applied to Delaware's sandy coastal plain soils can leach nitrate rapidly into the shallow unconfined aquifer that underlies much of the state and supplies many private wells.
Key Facts
| EPA Nitrate MCL | 10 mg/L as N |
| Delaware poultry density | Among the highest poultry-per-square-mile concentrations in the US |
| Sussex County risk | Highest agricultural intensity — sandy soils allow rapid nitrate percolation to shallow aquifer |
| Delaware Inland Bays | Documented nitrate concerns from agricultural and residential nitrogen sources |
| State oversight | Delaware Division of Public Health (DDPH) |
Why This Matters in Delaware
Delaware is a small state with an extremely high density of poultry production — particularly in Sussex County, which has more chickens than people by a very wide margin. Poultry litter is applied as fertilizer across Delaware's agricultural lands. The state's sandy coastal plain geology provides minimal filtration as water moves from the surface to the shallow aquifer. Delaware's Inland Bays region has faced documented nitrate concerns from agricultural and residential nitrogen sources. DDPH and the Delaware Department of Natural Resources and Environmental Control (DNREC) work together on nitrate monitoring and mitigation. Private well users in Sussex County especially should test annually.
Critical — Infants Under 6 Months
Do not use tap water that exceeds 10 mg/L nitrate-nitrogen to prepare infant formula or feed infants under six months. Boiling will concentrate nitrate — do not boil. Use bottled water or a certified reverse osmosis system (NSF/ANSI 58) until the issue is resolved.
Delaware Utilities With Nitrate Violation Records
The utilities listed below have at least one nitrate violation on record in EPA's SDWIS database. Violations may be open or resolved — see individual utility pages for current status and risk level.
Wilmington Water Department
Wilmington · 107,976 served
Dover Water Department
Dover · 39,491 served
Artesian Southern Sussex Regional
Bethany Beach · 18,215 served
Middletown Water Department
Middletown · 17,700 served
Sussex Shores Water Company
Bethany Beach · 12,450 served
Smyrna Water Department
Smyrna · 11,813 served
How Nitrate Gets Into Drinking Water
Agricultural fertilizer and manure runoff
Nitrogen-based fertilizers and animal waste applied to Delaware cropland can leach into groundwater or run off into surface water supplies. This is the dominant nitrate pathway in most agricultural regions.
Septic system effluent
Failing or poorly sited septic systems release nitrogen-rich wastewater near drinking water wells. Rural areas with high well density and aging septic infrastructure face elevated risk.
Concentrated animal feeding operations (CAFOs)
Large livestock facilities generate significant waste. Lagoon leaks and overapplication of manure to nearby fields can create localized nitrate hotspots in groundwater.
Natural geological deposits
In some regions, naturally occurring nitrogen compounds in soil and bedrock contribute background nitrate levels to groundwater independent of agricultural activity.
Who Should Pay Closest Attention
Private well users in Sussex County and eastern Kent County — Delaware's most intensively farmed regions — should test for nitrate annually. Households with infants in these areas should use current test results to decide whether alternative water sources are needed for formula preparation.
Households with infants under six months
Pregnant residents
Private well owners in agricultural areas
Households near livestock operations or CAFOs
Rural residents on shallow groundwater wells
Households with older or failing septic systems nearby
How to Check Your Situation in Delaware
- 1
Identify your water utility. Use the ZIP lookup below or browse the Delaware utility directory on this site.
- 2
Read your utility's page on this site to see its current risk level and any open nitrate violations.
- 3
Review your utility's most recent Consumer Confidence Report (CCR) — mailed annually or available on the utility's website. It must disclose any MCL exceedances.
- 4
If you are on a private well, arrange testing at a Delaware Division of Public Health (DDPH)-certified lab. Your state health department maintains a list of certified labs. Annual testing is recommended in agricultural areas.
- 5
If you have an infant under six months, use bottled water or a certified RO system (NSF/ANSI 58) immediately as a precautionary measure — do not wait for test results if you are in a high-risk area.
- 6
If your utility issues a nitrate exceedance notice, follow their guidance and do not use tap water for infants until the issue is resolved.
Treatment Options
Carbon filters and boiling do not remove nitrate. Only the options below are effective.
NSF/ANSI Standard 58 — Reverse Osmosis
RO systems certified to NSF/ANSI 58 reduce nitrate by 85–95% at the point of use. Under-sink installation required. The most practical residential option for nitrate concerns.
Distillation
Distillation units effectively remove nitrate along with most other dissolved contaminants. Suitable for drinking and cooking water — not whole-house use.
Anion Exchange
Ion exchange systems designed for nitrate removal exchange nitrate ions for chloride on a resin bed. Effective as a point-of-entry system; requires periodic regeneration and monitoring.
Carbon filters do NOT remove nitrate
Standard pitcher filters, faucet filters, and under-sink carbon units — including those certified NSF/ANSI 42 or 53 — do not remove nitrate. Do not use these for nitrate reduction.
Frequently Asked Questions
Related Pages
Nitrate — National Overview
All U.S. utilities with nitrate records
Delaware State Overview
All utilities and water quality data
Lead in Drinking Water
A separate but common concern
Reverse Osmosis Guide
Removes 85–95% of nitrate
Well Water Guide
Private well testing and safety
All Contaminants
Complete reference library
Data Sources & Provenance
All data on this page is sourced from official U.S. government or public datasets.
Find Your Utility
State Regulator
Delaware Division of Public Health (DDPH) ↗