Rely On Well Water? Just As Your Furnace Needs To Be Sized, So Does Your Well Pump


Connecting your residence to well water involves considerations beyond merely digging the well. The pumping system utilized, the well capacity and correct sizing of that system to your home’s needs all affect your ultimate satisfaction.

Shallow-well systems, the most common, are used in wells with depths around 25 feet and normally incorporate a jet pump located at ground level, drawing well water up through a suction pipe. Proper sizing involves determining your household’s peak water demand, then matching a pump with sufficient volume and pressure while not exceeding your well’s water capacity.

Water Demand

The simplest method of estimating household water needs is by fixture count. The pump’s capacity in gallons per minute (GPM) should equal the total number of water fixtures in your home — faucets, bathtubs, toilets, etc.

The second method calculates peak demand at hours of the day when usage is highest. The average GPM flow rate of all fixtures for a seven-minute span during peak hours is totaled. The total figure is divided by seven and matched with a pump that supplies an equivalent GPM.

Well Capacity

A well that can’t produce water fast enough to keep up with the GPM demands of your household will run dry unless well capacity is taken into consideration while sizing. Where well water is insufficient, the pump is sized according to the existing capacity, and the deficit — the difference between well capacity and house demands — is made up by installing an inline pressurized storage tank in the house.

Water Pressure

The distance between the well and the house and the water pressure demands of various appliances determine optimum pump pressure. Generally, the inlet side of the plumbing fixture located farthest from the pump in the household plumbing system should have a water pressure of at least 20 psi. Well water pressure is also affected by factors such as the condition of plumbing and the depth of the well.