NOTE: “Top of Well” also means “pitless adaptor level”.
“Service Inlet” also means “storage tank inlet”
Standing or Static Water Level – distance from top of well to natural water level when pump is not operating.
Drawdown distance – distance water level drops while pump is operating.
Drawdown level – standing water level plus drawdown.
Submergence – distance submersible pump intake screen is installed below drawdown level.
Elevation – vertical distance between top of well to pump inlet screen.
Pump Setting – distance from top of well to pump inlet screen.
Pumping Level – distance from drawdown level to service inlet.
Service Pressure – pressure (in PSI) at service inlet.
Friction Loss – loss of pressure due to friction of water flowing through pipe and fittings.
Total Discharge Head – discharge head (in feet) delivered when pump is operating at desired capacity.
Horizontal Pipe Run – horizontal distance between service inlet and well.
NOTE: PSI can be converted to equivalent feet of head by multiplying by 2.31.

1. WHAT IS THE SIZE OF THE WELL? The inside diameter of the well must be known so that the proper size pump, injector, cylinder or drop pipe and foot valve can be determined.
2. WHAT IS THE PUMPING LEVEL? The vertical distance in feet from the pump to the water level while the pump is operating. If the pump is installed away from the well and is on higher ground, this elevation must also be included. Most wells draw down while being pumped so this must not be confused with the standing water level.
3. WHAT SHOULD BE THE AVERAGE DISCHARGE PRESSURE? Usual average discharge pressure is 40 lbs. – halfway between the 30 lbs. To 50 lb. switch settings of most water systems. When the tank is installed away from the pump at a higher level, or when the house or yard fixtures are above the pump and tank, a greater pressure is needed and a larger pump must be used.
4. WHAT CAPACITY IS REQUIRED? The discharge capacity of the pump in gallons per hour that is needed for satisfactory service. The pump should have enough capacity so that it can deliver the total water requirement in 2 hours of continuous operation. See table of water requirements at right.

ILLUSTRATION DEFINITIONS

MAXIMUM TOTAL HEAD is the maximum pressure that can be developed by the pump. This is always given in feet of head rather than in pounds. The pump selected must have a maximum total head greater than the sum of the PUMPING LEVEL and the TOTAL DISCHARGE HEAD. (Shown in illustration as Total Head.)

When figuring PUMPING LEVEL the following conditions must be considered:

STANDING WATER LEVEL is the distance from the top of well to the top of the water when the pump is not operating.

DRAWDOWN is the distance the water level drops below the standing water level while pump is operating.

SUBMERGENCE is the distance the injector, submersible pump, or foot valve is installed below the pumping level.