What Size Well Pump Do You Need?

It is depending on your water home needs. Pumps are rated in GPM (gallons per minute).

A key to selecting the right size pump is to figure the gallons per minute of water required at peak periods. A pump should be selected to meet normal peak demand for the household, rather than average use. There are two common methods for sizing a residential pump system.

* Residential Capacity Based on Fixture Count

The capacity of the pump system in gallons per minute should equal the number of fixtures in the home. This must take into account all use for the kitchen, bath, appliances, outside irrigation, a pool, and special fixtures, such as a hot tub. In this model, modern home with two bathrooms (three outlets each), kitchen sink, dishwasher, washing machine, laundry tub, and two outside hose outlets would require a capacity of 12 gallons per minute, based on the 12 fixtures or outlets.

• Residential Capacity Based on Peak Demand

A second model, using the same fixtures and plumbing as the previous example, calculates capacity based on seven-minute peak demand. The peak time for household water use is normally in the morning, when the family rises, or in the evening when all are home. Seven minutes is the average high water use timeframe for a shower or automatic washer. (Table Below)

Although you’ll need a large enough pump to meet your home water needs, an oversized pump will create energy inefficiencies and reduced performance. When replacing a pump, you should choose a unit with the same horsepower. However, additional horsepower may be necessary if you are adding new appliances or family members. The longer the distance to transport water, the more horsepower will be needed.

If replacing a pump, you can check the identification plate on your pump to determine the horsepower. Keep in mind that submersible pumps may require either three wires or two wires, so you’ll determine how many wires your replacement pump will need.