Well water in Sussex County, Delaware
1in2
Testing strongly recommended
tested well samples in Sussex County exceeded the EPA limit for nitrate (10 mg/L), based on public data from USGS Water Quality Portal.
6,622 test results across 15 contaminants from at least 464 wells, 1931 to 2026; nitrate has the most at 1,465. Data refreshed September 15, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
An estimated 73,311 people in Sussex County get their drinking water from a private well, per USGS 2015 county water use. That is about 34% of residents.
Separately, the USGS national arsenic model estimates that 7% of the 73,311 people on private wells in Sussex County draw water above 10 ug/L (the model's range is 4% to 10%), from geology and well depth rather than local tests.
What individual samples found
Each row summarizes every public sample for that contaminant inside Sussex County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.
| Contaminant | Above limit | Samples | Detected | Median | Highest | Limit |
|---|---|---|---|---|---|---|
| Nitrate 1931 to 2026 | 1,465 | 89% | 7.4 | 184 | 10 mg/L EPA limit | |
| PFOA 2018 to 2019 | 23 | 43% | 0 | 40 | 4 ng/L EPA limit | |
| PFOS 2018 to 2019 | 23 | 26% | 0 | 59.0 | 4 ng/L EPA limit | |
| Lead 1982 to 2026 | 271 | 56% | 0.039 | 1,420 | 15 ug/L EPA limit | |
| Arsenic 1987 to 2024 | 213 | 26% | 0 | 22 | 10 ug/L EPA limit | |
| Copper 1982 to 2026 | 254 | 53% | 0 | 2.35 | 1.3 mg/L EPA limit | |
| Fluoride 1944 to 2024 | 576 | 30% | 0 | 1.9 | 4 mg/L EPA limit | |
| Uranium 2000 to 2024 | 71 | 38% | 0 | 0.318 | 30 ug/L EPA limit | |
| Radium (226 + 228) 2000 to 2018 | 56 | 57% | 0.098 | 3.8 | 5 pCi/L EPA limit | |
| E. coli 2001 to 2024 | 14 | 0% | 0 | 0 | 0 MPN/100mL EPA limit | |
| Chloride 1931 to 2026 | no limit | 1,049 | 99% | 15 | 9,500 | 250 mg/L nuisance level |
| Iron 1931 to 2026 | no limit | 936 | 66% | 10 | 120,000 | 300 ug/L nuisance level |
| Sodium 1931 to 2026 | no limit | 920 | 100% | 9.04 | 5,500 | 20 mg/L health guideline |
| Manganese 1969 to 2026 | no limit | 695 | 98% | 20.3 | 1,160 | 300 ug/L health guideline |
| Radon 1988 to 2018 | no limit | 56 | 96% | 198 | 460 | 2,000 pCi/L health guideline |
Over time
Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.
| Contaminant | before 2000 | 2000s | 2010s | 2020s |
|---|---|---|---|---|
| Nitrate | 44%596 samples | 20%220 samples | 53%477 samples | 24%172 samples |
| Fluoride | 0%295 samples | 0%123 samples | 0%147 samples | 0%11 samples |
| Lead | 3%114 samples | 13%71 samples | 0%33 samples | 0%53 samples |
| Copper | 2%114 samples | 0%53 samples | 0%33 samples | 0%54 samples |
| Arsenic | 2%94 samples | 3%59 samples | 0%33 samples | 0%27 samples |
| Uranium | n/a | 0%28 samples | 0%33 samples | 0%10 samples |
Nitrate above the limit in Sussex County fell from 53% of 477 samples in the 2010s to 24% of 172 in the 2020s.
Fluoride, lead, copper, arsenic, uranium have held within a few points between the two most recent periods with enough samples.
Closer than the county
See the sampled wells near your address
The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.
Check my addressWhat this means
The contaminants most often above their limit here are nitrate (41% of 1,465 samples), pfoa (35% of 23 samples), and pfos (22% of 23 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.
Chloride, Iron, and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.
What to test for in Sussex County
- 1Nitrate41% of 1,465 local samples were above the limit.
- 2PFOA35% of 23 local samples were above the limit.
- 3PFOS22% of 23 local samples were above the limit.
- 4Lead4% of 271 local samples were above the limit.
- 5Arsenic2% of 213 local samples were above the limit.
- 6Copper<1% of 254 local samples were above the limit.
- 7Coliform bacteriaRecommended for every private well, every year.
- 8Volatile organic compounds (VOCs)1,030 leaking underground storage tank sites on record locally.
Test your Sussex County well for nitrate, PFOA and PFOS
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.
Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.
Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.
Where to get a well tested in Delaware: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Sussex County numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Sussex County
51,833 domestic wells in Sussex County are on record with the state since 1972. the typical well is 65 feet deep (one in ten goes past 110 feet).
In a typical Sussex County well, the median yield is 40 gallons per minute, <1% of wells yield under 3 gallons per minute and usually need a storage tank.
Find your own well's report
The state keeps the driller's report for most wells drilled since 1984. It tells you how deep your well is, where bedrock starts, and how much water it makes, which decides what treatment can work.
- Open DNREC well permits and choose Water Well.
- The report lists depth, screen, static water level and the pump test.
Delaware has permitted every well since 1966.
The rock under Sussex County
Northern Atlantic Coastal Plain aquifer system
Semiconsolidated sand. Coastal plain sands like these give steady yields at moderate depth. Salt water and sodium are the usual issues near the coast, and nitrate where the water table is shallow; arsenic and radon from bedrock are less common.
Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the county centroid. A single well can sit in a different unit, especially near a boundary.
Official help in Delaware
Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.
- Private Drinking Water, Delaware DPH
Contamination sources on record in Sussex County
DNREC leaking tank facilities records 1,030 leaking underground storage tank sites in Sussex County, among 1,030 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.
- 1,030
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
Treatment that fits the local profile
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
PFOA
Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
PFOS
Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
Lead
Point-of-use reverse osmosis; Certified lead-removal carbon filter; Neutralizing filter to raise pH and stop leaching
Arsenic
Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Systems we would look at first
Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For nitrate
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For nitrate
Aquasana SmartFlow reverse osmosis
under-sink or countertop, about $225
Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.
For PFOA
Aquasana Claryum 3-Stage under-sink filter
under-sink or countertop, about $175
Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.
For PFOA
Whole-house PFAS carbon system
whole-house, at the point of entry, about $3,000
Granular activated carbon certified to NSF/ANSI 53 for PFOA and PFOS; replace media on schedule.
For PFOA
Aquasana HealthShield whole-house filter
whole-house, at the point of entry, about $2,099
Whole-house carbon system the maker certifies to reduce PFAS (PFOA and PFOS) and VOCs at every tap; a UV option adds bacteria protection.
For lead
Acid neutralizing filter
whole-house, at the point of entry, about $1,200
Raises pH so plumbing stops leaching lead and copper.
Free, no obligation
Get on the list for a free in-home water test in Sussex County
No water treatment company serves Sussex County through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Sussex County, and you get an email naming it first.
Common questions
How deep are wells in Sussex County?
The typical domestic well in Sussex County is 65 feet deep, based on 51,833 wells reported to the state since 1972. One in ten is deeper than 110 feet.
Is there arsenic in well water in Sussex County?
Arsenic was detected in 26% of 213 public well samples in Sussex County, and 2% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.
How high is radon in well water in Sussex County?
The median radon level across 56 public samples in Sussex County was 198 pCi/L, with a high of 460 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Sussex County?
Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.
Counties near Sussex County
Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.
Want the numbers themselves? Download the Delaware dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 6,622 samples in Sussex County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
- USGS national arsenic model (Ayotte 2017): estimated share of 73,311 people on private wells in Sussex County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
- Delaware DNREC non-public well permits: 95,136 well records in Sussex County, 51,833 domestic. Non-public well permits and completion reports from the Delaware Department of Natural Resources and Environmental Control. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 18, 2026.
- DNREC leaking tank facilities: 1,030 regulated sites located in Sussex County. Leaking underground storage tank facilities from the Delaware Department of Natural Resources and Environmental Control. Retrieved September 18, 2026.
Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.