Pressure tanks also known as accumulator tanks will give you a smoother water flow, quieter operation, save your power and will extend the life of your pump. Whether you have a 12 volt, 24 volt or 240 volt pressure pump set up, a pressure tank is a must for every system to protect your pump.
When you turn on your tap the water accumulated in the pressure tank is first released from the tank before the pump has to turn on. If there is enough water in the pressure tank for the application (say washing your hands) then the pump will not have to start. When the tap is turned off or if there is excess pressure in the line than what is being used at a given time, the back pressure is absorbed back into the pressure tank thus protecting the pump.