The basic (Standard Pressure) residential water well system (with a steel sleeve wellhead) looks like the diagram below. The submersible pump pushes water up through the drop pipe to the surface. The check valve keeps water from flowing back into the well. The pressure switch turns the pump on when the pressure drops and off when the pressure builds up. This happens over a 20 psi range. The pressure is stored in the pressure tank – typically 84 or 116 gallons. If the system builds too much pressure, the relief valve will release the excess pressure to prevent the pump from being damaged. If the well produces less water than your water demand over a period of time and the well temporarily runs dry, a PumpSaver device will shut off the pump to protect the pump from overheating (and potentially weakening the casing and causing it to collapse).
This has been the tried and true system for generations. It works in almost every situation. But it does have some drawbacks.
If your well produces less water than your demand at any given moment, the PumpSaver will protect the system from damage… but you are still temporarily out of water. Or when the pump finally wears out and needs replaced, you are left without water until the pump can be replaced. In these situations, it is beneficial to have a storage tank system with your well.
Another drawback of the standard pressure system is that the pump turns on and off as the pressure in the pressure tank rises and falls by 20 psi. During high usage times (such as long showers or lawn irrigation), this results in a high number of pump starts and stops. These hard starts/stops are what wears pumps out and shortens their lifespan. This 20 psi pressure range can (at best) be frustrating in the shower and (at worst) problematic for your irrigation system since your sprinklers will throw farther/shorter as the pressure rises/falls. This can results in dry/brown spots in your lawn. A solution to all of these problems can be a constant pressure system operated off of a variable frequency drive (VFD).The video to the right compares and contrasts a standard pressure well system with a constant pressure well system.