Submersible pumps are frequently used in underwater well systems, and the head on such a submersible pump is an important quantity to determine, as it tells you how well your pump works.The head is a measurement of water pressure, usually measured as a distance above a reference point. The static head can help you determine how much water is available for a water pump, and calculating this quantity is a straightforward process.

Find the total well depth. This is generally specified during construction of the well. As an example, say the well is measured to be 20 feet deep.

Determine the amount of air in the top well casing (the distance between the water level and the top of the well) and the well bottom clearance (the distance between the well pump and the bottom of the well), and find the sum of the two quantities. As an example, if we assume the two quantities are both 5 feet, the sum of the two is 10 feet. Call this result "A."

Subtract result "A" from the total well distance. In our example, subtracting 10 feet from 20 feet gives 10 feet. This is the head of the submersible pump.