I have a cistern. There is a 1/2 hp pump that is located under the house. The pressure tank was faulty and I just replaced it. There is a pressure switch attached to the pump. It says that it is a 20-40 lb switch. My question is: How do I know what the pressure is set at? We have only lived here a year and not sure that they didn't set it up to more. The new pressure tank instructions say that the pressure inside the tank should be 18 lbs for a 20-40 lb pressure switch should be 18 lbs. It doesn't seem like the water pressure inside the house is as high as it was.