Short definition
A dug well is a wide-bore, shallow well — typically 3 to 10 feet across and 10 to 30 feet deep — excavated by hand or backhoe and lined with stone, concrete tile, or brick. Most pre-1950 rural Washington farmsteads had one. Almost all have since been abandoned or decommissioned in favor of drilled wells, because dug wells are vulnerable to surface contamination.
What it is
Picture a brick- or stone-lined cylinder dropping straight down to the water table. Yield comes from the surface area of the lining in contact with the surrounding aquifer — bigger diameter, more inflow. The water table itself is the supply, so depth is set by how deep the table sits in dry summer conditions.
The defining weakness is the open bore. A wide, shallow, lined well has a much larger contact area with surface runoff than a sealed drilled well, and lining joints leak. Surface water carries coliform bacteria, agricultural fertilizer, pesticides, and silt straight into the supply.
Why it matters to a homeowner
If you’re buying or already own a property with an old dug well, three things to know:
- Water quality testing usually fails. Coliform-positive results are the rule, not the exception, on legacy dug wells. WA county health departments routinely recommend abandonment.
- Yield is seasonal. When the water table drops in late summer, a 25-foot dug well can run dry while a 200-foot drilled well across the road keeps producing.
- Decommissioning is regulated. You can’t just fill in an old dug well — Washington’s well construction rules (WAC 173-160 Part 2) cover sealing requirements to protect the aquifer.
Some off-grid landowners keep a dug well for irrigation while running a separate modern drilled well for potable use. That works, as long as the two systems are physically separated and the dug well isn’t presented as drinking water.
When you’ll encounter this term
- A “spring house” or covered concrete cap in a corner of an old farmstead.
- A real-estate inspection identifies the dug well, and the buyer asks the inspector and the county health department what to do.
- A pre-1950 home sale where the buyer’s loan requires a passing well water test — the dug well typically fails, triggering negotiation.
Common failure modes
- Coliform contamination from surface runoff entering the open bore.
- Seasonal yield drop when the water table falls below the well bottom in summer.
- Lining collapse as old brick or stone walls fail with age.
- Silt clogging at the suction strainer.