Arsenic in 30 Seconds
- You can't see, smell or taste it. A lab test is the only way to know.
- It's natural here. State geologists trace it to two deep aquifers — the Aquia and Piney Point — that supply many Eastern Shore and southern Anne Arundel homes.
- The limit is 10 parts per billion (ppb). That's the EPA and Maryland drinking water standard.
- The risk comes from drinking it over years — linked to several cancers, heart disease and diabetes.
- It's very treatable once you know your level and the form of arsenic in your water.
Where Arsenic Shows Up on the Eastern Shore & in Anne Arundel County
Arsenic isn't spread evenly across Maryland. A Maryland Geological Survey study that evaluated data from more than 4,200 wells found that only two Coastal Plain aquifers have widespread arsenic above the 10 ppb standard: the Aquia and the Piney Point. The shallower Columbia and the Magothy and Potomac aquifers showed no exceedances.
The Aquia aquifer band
Elevated arsenic in the Aquia runs in a band from the Eastern Shore, under the Chesapeake Bay, into Southern Maryland. The Aquia is a major source of water for homes on Kent Island and across Queen Anne's County.
The Piney Point aquifer
The Piney Point has a similar but narrower band farther southeast, with smaller pockets in Talbot and Queen Anne's counties. The study's highest Piney Point reading was 33 ppb, in Dorchester County.
The Mayo Peninsula, Anne Arundel County
A separate hot spot sits on the Mayo Peninsula, where the state recorded the highest Aquia arsenic in the study: 131 ppb — 13 times the standard. When the Anne Arundel County Department of Health tested 71 wells in Saunders Point in 2006, 35 were over the limit, and it later found 38 more wells over the standard around Mayo and Shoreham Beach Roads.
Counties with detections
University of Maryland Extension lists arsenic detections in wells in Anne Arundel, Caroline, Dorchester, Kent, Queen Anne's and Talbot counties, among others. A state test well in Kent County screened in the Monmouth aquifer also measured 16 ppb.
Does Well Depth Matter?
Sometimes, a lot. It depends on where you live:
- Saunders Point / Mayo: about half of the shallow wells (150 feet or less) exceeded the standard, while wells deeper than 300 feet tested acceptable. Since January 1, 2008, new and replacement wells there must be at least 300 feet deep and meet the arsenic standard.
- The main Aquia and Piney Point bands: the state found no clear pattern of arsenic changing with depth, so drilling deeper isn't a reliable fix everywhere.
- New wells: a new well can't get its Certificate of Potability if arsenic is over 10 ppb unless treatment is installed.
A deeper well can be the right answer in some neighborhoods. In others, treatment is far cheaper and more certain. We'll help you weigh both.
Why Arsenic Matters for Your Health
The EPA classifies inorganic arsenic as a known human carcinogen. The concern is long-term drinking — years of exposure, not one glass. Long-term exposure above the standard is linked to:
- Skin, bladder, kidney, liver and lung cancers
- Skin changes such as discoloration and thickening
- Possible links to heart and blood vessel disease and diabetes
Testing for Arsenic: What to Ask For
- Use a Maryland-certified lab.
- Ask for arsenic speciation if you're treating. Labs usually report total arsenic only. Knowing how much is arsenic III versus arsenic V helps pick the right system — and that matters a lot here (see below).
- Buying or selling? Ask what's included. Maryland now requires a well water test before most home sales, but don't assume arsenic is on the list — confirm it with the lab, especially in the Aquia and Piney Point areas.
- Retest periodically — every 3 to 5 years, or more often in known high-arsenic areas — and after any treatment is installed.
- More testing may be coming. Under the Private Well Safety Act, Maryland must adopt county-specific testing standards by December 31, 2026, and arsenic is one of the contaminants the law names.
The Local Detail Most Arsenic Systems Miss
Arsenic comes in two main forms. Arsenic V is relatively easy to remove. Arsenic III is harder — many filters let it slip through unless it's converted to arsenic V first.
| ~80%of the arsenic in Aquia aquifer samples was arsenic III — the hard-to-remove form | ~70%of the arsenic in Piney Point aquifer samples was arsenic III |
That's why an off-the-shelf filter or a basic reverse osmosis unit can underperform on Shore water. The system has to handle arsenic III directly, or include a pre-oxidation step that converts it first.
Arsenic Treatment Options, Compared
| Option | Strengths | Watch out for |
|---|---|---|
| Iron oxide adsorptive media (whole house) |
Removes both arsenic III and V with no pre-oxidation. No regeneration, so no arsenic-laden backwash. Simple to run. | Media is replaced every few years, depending on arsenic level and water use. |
| Reverse osmosis (kitchen tap) |
Lower-cost way to protect drinking and cooking water. Also reduces many other contaminants. | Works best on arsenic V, so arsenic III may need pre-oxidation. Only treats one tap; fridge and ice maker need a line from it. |
| Activated alumina | Effective arsenic removal. | Needs pre-oxidation for arsenic III; less effective at higher pH; more maintenance. |
| Anion exchange | Effective on arsenic V. | Needs pre-oxidation; weakened by sulfate; if regeneration is missed it can release arsenic back into the water. |
| Water softener or iron filter alone | — | Not designed for arsenic. Don't count on them to bring you under 10 ppb. |
See our whole-house arsenic filters and reverse osmosis systems for the equipment we install.
Whole house or kitchen tap?
Because the risk is from drinking, a properly set-up reverse osmosis system at the kitchen sink can be enough for many homes. A whole-house system makes sense when you want every tap safe to drink from — bathroom sinks where kids brush teeth, a wet bar, an outdoor kitchen, guests who don't know the rules — or when arsenic is high and you're already treating for iron, sulfur or hardness. Some families do both. We'll lay out the options honestly.
How Lifewell Handles Arsenic
| 1 | Lab test with speciation. Total arsenic plus arsenic III vs. V, along with iron, manganese, pH, sulfate, hardness and phosphate — the things that affect how arsenic media performs. |
| 2 | Review your options. Whole-house media, reverse osmosis, or both — and in places like Mayo, whether a deeper well might make more sense. |
| 3 | Design the full system. Arsenic treatment sized for your water use and placed correctly with any iron, sulfur or pH equipment, so one doesn't foul the other. |
| 4 | Install with certified components. Look for systems certified to NSF/ANSI Standard 53 or 58 for arsenic reduction. |
| 5 | Prove it works — and keep it working. Retest after installation, then on a schedule, and replace media before it's used up. Arsenic media doesn't give you a warning sign when it's spent. |
Why Shore & Anne Arundel Homeowners Call Lifewell for Arsenic
- Based in Queenstown — right on top of the Aquia aquifer that drives so much of the arsenic here.
- We test for the form, not just the amount, so your system is built for arsenic III.
- Honest options. If a kitchen RO is all you need, that's what we'll recommend.
- Master plumber–led installation, licensed and insured.
- Long-term follow-through — retesting and media replacement so protection doesn't quietly run out.
Frequently Asked Questions
Is there arsenic in Eastern Shore well water?
In some areas, yes. The Maryland Geological Survey found widespread arsenic above the 10 ppb standard in the Aquia and Piney Point aquifers, which supply many Eastern Shore homes. Detections have been reported in Queen Anne's, Talbot, Kent, Caroline and Dorchester counties. Only a test of your own well tells you your level.
Where is arsenic a problem in Anne Arundel County?
The Mayo Peninsula, including Saunders Point and the area around Mayo and Shoreham Beach Roads. The state recorded up to 131 ppb in the Aquia aquifer there, and county testing found dozens of wells over the standard, mostly shallower wells.
What is a safe level of arsenic in well water?
The EPA and Maryland drinking water standard is 10 parts per billion (0.010 mg/L). Lower is better, since the health risk comes from long-term drinking.
Is it safe to shower in water with arsenic?
Health agencies say arsenic isn't easily absorbed through skin, so bathing, showering and laundry don't meaningfully add to exposure. The concern is water you drink or cook with.
Does boiling water remove arsenic?
No. Boiling evaporates water and leaves the arsenic behind, which makes it more concentrated.
Do I need whole-house treatment or just reverse osmosis?
Because the risk is from drinking, a properly set-up kitchen RO system is enough for many homes. Whole-house treatment makes sense if you want every tap safe to drink from or arsenic levels are high. Local arsenic is mostly arsenic III, so an RO may need pre-oxidation to work well.
Will a deeper well fix arsenic?
In the Saunders Point area, wells deeper than 300 feet tested acceptable, and new wells there must be at least 300 feet deep. Elsewhere in the Aquia and Piney Point bands, the state found no clear depth pattern, so a deeper well isn't a guaranteed fix.
Will a softener or iron filter remove arsenic?
Not reliably. They aren't designed for arsenic. You need a dedicated arsenic system such as iron oxide adsorptive media or reverse osmosis, which can be combined with iron and softening equipment.
How long does arsenic media last?
Typically a few years, depending on your arsenic level, water chemistry and use. Media gives no warning when it's spent, so periodic retesting is important.
Is arsenic included in Maryland's home-sale well test?
Don't assume so. Maryland requires a well water test before most home sales, but confirm with the lab that arsenic is included, especially in Aquia and Piney Point areas. Statewide county-specific testing standards are due by the end of 2026.
Know Your Arsenic Number
Arsenic is invisible, but it's easy to find and very treatable. Get your well tested and we'll walk you through every option.
Sources
- Maryland Geological Survey — Arsenic in Ground Water in the Coastal Plain Aquifers of Maryland (RI 78, 2010)
- Maryland Geological Survey — Arsenic in Maryland groundwater and interactive arsenic map
- Anne Arundel County Department of Health — Arsenic in Well Water in the Saunders Point Area
- University of Maryland Extension — Arsenic Water Treatment for Individual Wells in Maryland
- Maryland Geological Survey / MDE — Test-well fact sheet, Kent County
- Illinois Department of Public Health — Arsenic in Groundwater (bathing and skin contact)
- Maryland Dept. of Legislative Services — Private Well Safety Act of 2023 fiscal & policy note
This page is general information, not medical advice. If you're concerned about arsenic exposure, talk to your doctor.