If you are replacing an existing well pump and are not making any significant alterations to your home, you may simply look at the specifications of the old pump to see what kind of replacement is necessary. If it is a new installation or you are creating a bigger space with more plumbing needs, there are a few things to know. A jet pump sits above ground or in the basement. There are also well jet pumps and submersible jet pumps. Water depth will determine whether you require a shallow jet pump or a deep well jet pump. Well pumps have motors ranging in horsepower. Bigger is not always better. The pump should suit the needs of the home. A three to four bedroom home with five to six plumbing fixtures that deliver water will typically need an 8-12 GPM (gallon per minute) capacity pump.