Well water in Howard County, Maryland
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Testing recommended
tested well samples in Howard County exceeded the EPA limit for lead (15 ug/L), based on public data from USGS Water Quality Portal.
2,107 test results across 12 contaminants from at least 116 wells, 1944 to 2020; nitrate has the most at 867. Data refreshed September 15, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
An estimated 66,244 people in Howard County get their drinking water from a private well, per USGS 2015 county water use. That is about 21% of residents.
Separately, the USGS national arsenic model estimates that <1% of the 66,244 people on private wells in Howard County draw water above 10 ug/L (the model's range is <1% to 1%), from geology and well depth rather than local tests.
What individual samples found
Each row summarizes every public sample for that contaminant inside Howard 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 |
|---|---|---|---|---|---|---|
| Lead 1988 to 2019 | 103 | 26% | 0 | 20 | 15 ug/L EPA limit | |
| Nitrate 1944 to 2019 | 867 | 83% | 1.7 | 57.5 | 10 mg/L EPA limit | |
| Fluoride 1951 to 2019 | 178 | 63% | 0.1 | 0.8 | 4 mg/L EPA limit | |
| Copper 1952 to 2019 | 113 | 73% | 0.02 | 0.42 | 1.3 mg/L EPA limit | |
| Uranium 1957 to 2019 | 11 | 45% | 0 | 6 | 30 ug/L EPA limit | |
| Chloride 1944 to 2019 | no limit | 179 | 100% | 4.6 | 250 | 250 mg/L nuisance level |
| Iron 1944 to 2019 | no limit | 179 | 93% | 12 | 18,000 | 300 ug/L nuisance level |
| Manganese 1951 to 2019 | no limit | 177 | 90% | 11 | 2,400 | 300 ug/L health guideline |
| Sodium 1951 to 2019 | no limit | 176 | 100% | 5 | 70 | 20 mg/L health guideline |
| Radon 1988 to 2020 | no limit | 107 | 99% | 3,400 | 42,000 | 2,000 pCi/L health guideline |
Sampled fewer than 10 times, too few to summarize: Arsenic (9), Radium (226 + 228) (8).
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 lead (8% of 103 samples) and nitrate (7% of 867 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.
The median radon reading (3,400 pCi/L) is above the 2,000 pCi/L level at which treatment is recommended. Radon in water raises indoor air radon when it is used for showers and laundry.
What to test for in Howard County
- 1Lead8% of 103 local samples were above the limit.
- 2Nitrate7% of 867 local samples were above the limit.
- 3Coliform bacteriaRecommended for every private well, every year.
- 4RadonMedian local reading is 3,400 pCi/L.
- 5ChlorideDetected in 100% of local samples.
- 6IronDetected in 93% of local samples.
- 7ManganeseDetected in 90% of local samples.
Test your Howard County well for lead, nitrate and coliform bacteria
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 Maryland: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Howard County numbers, $29. Every line explained, ranked by what matters, with the fix for each.
The rock under Howard County
Piedmont and Blue Ridge crystalline-rock aquifers
Igneous and metamorphic-rock. Granite and similar crystalline rock hold water only in fractures. Wells are deep and yields modest, and the rock itself is the source of arsenic, radon and uranium, which is why those three head the test list in bedrock country.
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 Maryland
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.
Contamination sources on record in Howard County
MDE Land Restoration Program sites records 68 regulated sites in Howard County, among 68 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.
- 68
- other remediation projects
Treatment that fits the local profile
Lead
Point-of-use reverse osmosis; Certified lead-removal carbon filter; Neutralizing filter to raise pH and stop leaching
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
Radon
Aeration (bubble-up or diffused) whole-house; Granular activated carbon whole-house (lower levels only)
Iron
Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
Manganese
Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
Systems we would look at first
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For lead
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For lead
Acid neutralizing filter
whole-house, at the point of entry, about $1,200
Raises pH so plumbing stops leaching lead and copper.
For lead
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 iron
Iron and manganese oxidizing filter
whole-house, at the point of entry, about $1,800
Air-injection or greensand media; fixes staining at the source.
Free, no obligation
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Common questions
How high is radon in well water in Howard County?
The median radon level across 107 public samples in Howard County was 3,400 pCi/L, with a high of 42,000 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Howard 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 Howard 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 Maryland dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 2,107 samples in Howard 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 66,244 people on private wells in Howard 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.
- MDE Land Restoration Program sites: 68 regulated sites located in Howard County. Brownfield, voluntary cleanup and Superfund sites from the Maryland Department of the Environment Land Restoration Program. 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.