Water pressure tanks are most commonly used on home water systems from a private well. These tanks may also be employed by systems on a water utility, but have added a booster pump for increased water pressure in the home. Most water tanks operate using a pressure switch that is plumbed into the water line. This switch senses low water pressure and operates the pump. Inside most pressure tanks is a rubber bladder. This bladder maintains system pressure and keeps the pump from running erratically.
Check the Tank
The tank should be physically inspected for any obvious signs of leaks or rust. In certain times of year, more especially summer when humidity values are high, the tank may sweat. You may have to wipe the tank down with a towel or large rag to check for leaks. Tanks with a hole in the metal side may exhibit a large brown to orange colored spot. This could be coming from a small pinhole in the metal. These small leaks can be fixed with the use of some water resistant type epoxies. Unfortunately, once these types of leaks begin to form, greater damage may have already occurred inside the tank. The tank, eventually, will have to be replaced.
Pressure Switch or Hot Pump
The pressure switch controls the pumps operation. Within the switch is a set of copper discs called contacts. These contacts are mechanically attached to a set of springs. The springs are set to open and close the contacts upon various interior water pressures of the system. Most pressure tanks will have a pressure gauge near the switch. Check the operation of the switch while watching the gauge. Remove the cover of the switch, as the gauge drops in pressure, the contacts should close. If the contacts fail to close, the switch may have to be adjusted or replaced. Adjustment procedures for the switch are typically located on the underside of the cover. Check the temperature of the pump. If the pump gets very hot during operation it may be shutting down. The pump will then reactivate once an internal high temperature switch automatically resets. The pump may have to be replaced if it is in this condition.
Pressure Tank Bladder
The rubber bladder in the pressure tank could be ruptured or empty of air if the pump is erratic in operation. If the pump comes on in short and frequent operation, the rubber bladder may be the cause. Remove all power to the pump motor and drain the water from the system. Identify the bladder's air filling stem. This air stem will look identical to the one on your vehicles tires. Use a tire pressure gauge to check the air pressure in the bladder. It should be between 30 PSI and 45 PSI depending on your size of pressure tank. If the bladder reads 0 PSI then fill the bladder with compressed air. If the bladder fails to hold any air pressure, the rubber bladder is damaged. You will have to replace the entire pressure tank.