How Deep Is a Water Well?

Typical depths by well type

Regional spread is huge. Minnesota's well handbook, for one state, lists wells from 15 feet to over 1,000 feet deep. Public-supply wells run deeper than home wells, with a USGS median of 202 feet.

What decides how deep a driller goes

A driller isn't aiming for a number. They're drilling until they reach a water-bearing layer that gives enough water and is protected from surface contamination. Three things decide where that is:

• The water table. HomeGuide notes shallow wells of 25 to 50 feet can work where the water table is high.
• Water quality. HomeGuide says drinking-water wells should be at least 100 feet deep in most areas. Shallow water is closer to septic systems, fertilizer and road runoff.
• Yield. A well that reaches water but can't keep up with the house gets drilled deeper. See well yield and recovery rate.

Depth also decides what pump you can use. Minnesota's handbook says shallow jet pumps are for water less than 25 feet down, deep-well jet setups for water levels under 200 feet, and that submersibles are the type most often used in drilled wells. A Flotec shallow-well jet pump manual caps total suction lift at 20 feet at sea level. That's why deep drilled wells usually have a submersible.

How to find your own well's depth

Start with paper, not a tape measure.

1. The well record. In most states the driller files a construction record with the depth, water level and geology. Minnesota requires the contractor to give one to the owner and the health department. Ask your state's health or natural resources agency for a records search by address.
2. Your closing papers. Look through the home purchase file for a well inspection or disclosure.
3. The equipment. Minnesota's health department suggests checking for information written on the pressure tank, control box or well room wall.
4. Neighbors and the last pump installer. Whoever pulled the pump last knows how much pipe came out.

Older wells may have no record at all. In Minnesota, for example, state well records weren't required before 1974.

If the paperwork is gone, a well contractor can measure the depth and the static water level. Doing it yourself means dropping a weighted line past the pump wire and drop pipe, and a snagged line can cost you a pump pull. Leave it to the pro.

What depth means for cost

Drilling is priced by the foot, so depth is the biggest line on the bill. HomeGuide's complete-well ranges go from $3,000 to $8,000 or more at 100 feet up to $15,000 to $40,000 at 500 feet. The full table is on our well drilling cost page.