A pressure tank is a tank designed to withstand a high enough pressure. This tank is equipped with a membrane (diaphragm) that will separate water and air. Water Pressure Tanks are in principle useful to stabilize water pressure on the tap. Inside the pressure tank there is usually a membrane that serves to maintain the durability of the Pressure Switch because when water is used a little, the pump does not need to work and Siwtch Pressure does not need to work so as to maintain the pressure switch resistance.