Well Water in Washtenaw County: What to Test and Why

Your well water comes from the Marshall sandstone, an old layer of sand and rock that sits deep underground. This sandstone formation stretches across several counties in southern Michigan, including here in Washtenaw County. Water moves slowly through the tiny spaces between sand grains in this rock.

The Marshall sandstone in this area stays clean because of the thick clay and mixed sediment layers sitting on top of it. These upper layers act like a shield, blocking pollution from roads, farms, and septic systems from seeping down to the water below. The rock itself does not release harmful metals or minerals into the water the way some other rock types do.

The water from this sandstone tends to be relatively simple in its mineral makeup. You may notice some iron or hardness depending on your exact location and well depth, but the Marshall aquifer generally produces water that is easier to manage than what you find in neighboring counties. For most people, a basic water test will show what you are working with so you can treat it if needed.

Good news for your well: testing in Washtenaw County shows no contaminants that exceed EPA health standards. No harmful bacteria, arsenic, nitrates, or other dangerous substances have been detected in the area's groundwater. Your water meets federal safety requirements based on the data available.

Since the mineral content data is not available, we cannot assess whether your water has quality-of-life issues like staining, scaling, or odd taste or smell. These problems depend on iron, sodium, and sulfate levels that haven't been measured yet. Getting a complete picture requires testing your own well.

Get your well tested through a state-certified lab to find out what's actually in your water. A basic health screen for bacteria and nitrate costs $50–100, while a comprehensive mineral and metals panel runs $200–400. Ask the lab to test for iron, manganese, sodium, and sulfate so you know exactly what you're drinking.