Common Well Water Problems in the DMV: Iron, Radon, and Bacteria
Private wells in Virginia and Maryland tap into different geology than the rivers that feed municipal systems, and that brings a different set of issues.
Well water and municipal water aren't just regulated differently, they're often chemically different too, because a well draws straight from local groundwater and bedrock instead of a treated river source.
Iron and manganese
Groundwater in parts of the Piedmont region, which covers much of Northern Virginia and central Maryland, tends to pick up dissolved iron and manganese from surrounding rock. It's rarely a health risk at typical levels, but it stains fixtures and laundry reddish-brown and can give water a metallic taste.
Radon
Radon is a naturally occurring radioactive gas that can dissolve into groundwater, particularly in areas with granite or certain other bedrock types common across the Piedmont. Regional groundwater studies in the broader Mid-Atlantic have found radon present in a meaningful share of tested wells. It has no taste or smell, so testing is the only way to know.
Bacteria and coliform
Virginia's only mandatory well test is a one-time coliform check at drilling. After that, bacteria can enter a well over the years through a cracked casing, a failing seal, or nearby surface runoff, especially after flooding. This is exactly why health officials recommend annual bacteria testing, not just a one-time check.
Nitrates
In agricultural areas, nitrates from fertilizer and septic systems can seep into groundwater. The EPA's health-based limit is 10 mg/L; above that, nitrates are a particular concern for infants.
The common thread
None of these show up unless you test for them specifically, and on a well, nobody is doing that testing for you automatically.
