The type of water equipment you have varies based on your water chemistry. You may have what is referred to as an aerator, which is simply a large storage tank with a second pump and tank arrangement to re-pressurize the water to your home, and a softener to make the water user-friendly. Or you may have a twin tank system that looks like two softeners, but may actually be a softener, pressure tank, and a sulfur removal tank. Either way, you have at least one pump, one pressure tank, and a pressure switch.