How do you determine the correct size of a water-well pressure tank?

The tank's cut-in and cut-out times are used to obtain the acceptance factor, multiplying the pump's output by its desired runtime and then dividing product of the output and runtime by the acceptance factor. As a standard, there should be two minutes of motor free operation for a 1hp pump.

If a motor cycles too often, it places added wear on the pump. The pressurized pump must store a given amount of water to prevent the motor from running automatically. The amount of water that must be stored is determined by the size of the pump. The larger the pump, the longer it needs before the motor begins running again.