How do I choose the right pump for my system?

To size a pump correctly you will need to determine your required flow rate and the amount of lift required.

Flow rate: The volume of water that travels through the pump in a given time (measured in gallons per minute or GPM).

Lift: The amount of lift required is referred to as Total Dynamic Head (TDH).

Determine Flow Rate:

There are a number of different methods to determine the desired flow rate. The key to selecting the right size pump is to figure out the gallons per minute of water required at peak periods. Although there are different methods to calculate flow, in general, the Water Systems Council bases selection for a residential system on total gallon usage during a seven minute peak demand period. As an example, one method calculates desired flow at 7 GPM for a 1 bathroom home and 17 GPM for a home with 3 or 4 bathrooms. After you determine your desired flow rate, make sure that your well is capable of supporting it.

Calculate Total Dynamic Head (TDH):

1. Vertical Lift/Elevation: The vertical distance between the pitless adapter to the top of the pressure tank.
2. Service Pressure: The average pressure switch setting X 2.31’
3. Pumping Level: The vertical distance in feet from the pitless adapter or well seal to the water drawdown level in the well that yields the flow rate required by the pump.
4. Friction Loss: Water flowing through piping will lose head depending on the size, type and length of piping, number of fittings, and flow rate. A friction loss table or calculator will be required for this calculation.

Total Dynamic Head (TDH) = 1 + 2 + 3 + 4

After you determine Flow Rate and Total Dynamic Head, contact an RC Worst pump expert. We will examine pump performance curves to help you find the perfect pump for your system.