Maryland Private Well Water Quality 2026

The Salisbury PFAS Crisis — Maryland’s Most Significant Well Contamination Event

In late 2024, Maryland well owners in Salisbury, Wicomico County, learned something their neighbours at Perdue AgriBusiness had known for over a year: PFAS from the company’s soybean processing facility had migrated into the surrounding groundwater. The Maryland Department of the Environment (MDE) had notified Perdue in August 2023 that its wastewater contained elevated PFAS — but residents only received notification letters in November 2024.

When Perdue tested private wells within the designated testing zone in October 2024, every single one of the nine properties tested came back above federal drinking water thresholds for PFOS, PFOA, or both. Six wells additionally showed elevated levels of PFHxS. On-site groundwater measurements at the Perdue facility recorded PFOS levels as high as 1,370 parts per trillion — more than 340 times the federal limit of 4 ppt — with PFOA up to 159 ppt.

As of November 2025, investigators from Langan Engineering identified the facility’s previous AFFF firefighting foam suppression system as the only site-related PFAS source found to date — though Perdue’s own published materials note the exact source of contamination has not been confirmed. The system has since been replaced. MDE designated Perdue a “responsible person” in September 2024, and a class action lawsuit filed on behalf of over 400 affected residents calls for Perdue to fund clean-up and provide medical monitoring for those exposed. As of early 2026, Perdue had completed testing at 679 properties and installed treatment systems at 91% of impacted homes within the testing zone — but the zone covers only a defined radius around the facility, and wells beyond that boundary have not been tested as part of this programme.

Nitrate Risk — A Critical Threat on the Eastern Shore

Maryland’s Lower Eastern Shore is heavily agricultural — a landscape of chicken houses, fertilised fields, and shallow groundwater. In two Eastern Shore counties, research published by the Center for Progressive Reform found that one in 25 private wells had nitrate levels above the EPA’s safe drinking water threshold of 10 mg/L. Nitrate at those levels can cause blue baby syndrome in infants under six months — a potentially fatal condition. Research also links sub-threshold nitrate exposure to elevated cancer risk, pregnancy complications, and thyroid disease.

The problem is compounded by the fact that nitrate is colourless, odourless and tasteless. There is no way to detect it without laboratory testing. Eastern Shore counties with intensive poultry and farming operations — including Wicomico, Somerset, Dorchester, and Queen Anne’s — present the highest nitrate risk to well owners.

Bacteria, Radionuclides, and Other Contaminants

A University of Maryland study testing 118 private wells across the state found total coliform bacteria in 25% of samples and fecal coliforms in 15% of samples — with 43% of all wells failing at least one federal health-based drinking water standard. The same research found 26% of wells outside the recommended pH range, which affects both water palatability and corrosion of household plumbing.

Separately, groundwater studies in Baltimore County found elevated levels of radionuclides — including Radium-226 — in approximately 15% of tested private wells. Radionuclides occur naturally in certain geological formations and are associated with elevated long-term cancer risk.

A 2024–2025 University of Maryland WATER Study project — testing water samples from 154 homes across all 23 Maryland counties — confirmed that while most samples fell below federal MCL thresholds, a meaningful percentage did not, and researchers noted that meeting legal limits does not guarantee water is fully safe.

Regulatory Situation for Maryland Well Owners

Private wells in Maryland are not regulated under the federal Safe Drinking Water Act or state law. MDE has no authority to mandate testing of residential private wells, and prior to 2023 Maryland ranked among the five states with the fewest protections for well owners.

That changed — partially — with the passage of the Private Well Safety Act of 2023 (HB 11/SB 483), signed into law in April 2023. The Act requires MDE to develop county-specific testing recommendations by December 2026 (covering manganese, radon, arsenic, mercury, and VOCs), establish an online well water quality database, and mandate water quality testing at the point of sale when a home with a well changes hands. It does not require routine testing by existing well owners.

Maryland has no state PFAS MCLs for private wells. Federal MCLs of 4 ppt for PFOA and PFOS apply only to public water systems. MDE’s guidance to private well owners is clear: testing and treatment remain the individual homeowner’s responsibility. The state does not fund or provide testing for private well owners as a general programme, though local county health departments may be able to signpost certified laboratories.

Check our Maryland municipal water quality page for city-by-city tap water data, including Baltimore, or use our live boil water notice tracker for active advisories across the state.

Known High-Risk Areas in Maryland

If you live near any of the following locations, well water testing is urgent — not precautionary.

How to Test Your Maryland Well Water — and What to Do Next

MDE recommends that all private well owners in Maryland test for bacteria and nitrate at least annually, and test for additional contaminants — arsenic, lead, radon, VOCs, and PFAS — at least once, with location-specific additions depending on local risk factors. Given the evidence of widespread bacteria contamination and the ongoing Salisbury PFAS event, those recommendations should be treated as a minimum, not a target.

Maryland’s Private Well Safety Act of 2023 requires MDE to publish county-specific testing recommendations by December 2026. Until those county-specific guidance documents are published, check with your local county health department — they can direct you to certified laboratories and advise on what additional contaminants are most relevant in your area.

For filter options, our well water filter guide covers reverse osmosis systems for PFAS and nitrate, UV disinfection for bacteria, and whole-house well systems for comprehensive treatment. You can also browse our full water filter solutions page or check your ZIP code for local water quality context.

For well water risks in neighbouring states, see our page on Michigan wells. Return to the private well water directory to find your state.