Water and Well Depth
Back to Simple Pump page.

What is the difference between well depth, groundwater depth, or static water level?

Well depth is defined as the full depth that the well was drilled or cased. "Depth to groundwater" and "static water level" are synonymous phrases and define the depth or distance from the top of the well to the level of water within the well.

This distinction is important because the static water level is the depth used to calculate the force required to pump water to the surface. This is true no matter the depth at which the pump cylinder operates. We normally recommend, to accommodate natural groundwater level decline, that the Simple Pumpô pump cylinder be installed at a depth of 36 feet below the static water level.

How do I determine the depth to groundwater or static water level?

Depth to groundwater is difficult to accurately determine without the benefit of a well sounding device. You can approximate the depth to groundwater from the well driller's drilling log when the well was initially drilled. If you don't have this information, contact a local well driller or practicing engineer to have the water depth confirmed by sounding or other measurement technique.

NOTE: If you want to determine your static water level yourself, you'll need: a small fishing weight, a 1 1/4" to 1 1/2" diameter bobber, 200 feet of a lightweight fishing line or kite string.


  • Attach the weight to the end of the line or string. Affix the bobber 1 inch above the weight.
  • Remove the well cap and lower the weighted end with bobber into the well casing.
  • When the bobber reaches the water level, the line will go limp. You'll feel a slack in the line.
  • At the point where you feel the slack, mark the line at the top edge of the casing (you can tie a small knot in the line, use tape or a marker)
  • Pull the line back up from the casing. Measure the length of the line from the bobber to the marked line. This is your static water level.