How to Precharge a Water System Tank

A water system tank is usually a tank with a bladder bag inside to help control water pressure. The bladder bag uses air to compress the water in the tank. When installing the water system tank, it is necessary to pre-charge the tank before turning on the water pump and filling the tank with water. Pre-charging is a matter of putting air into the bladder bag. Pre-charging and adjusting the bladder bag in a water system tank is similar to inflating or deflating an automobile tire.

Air compressor
Air pressure gauge

Instructions

- 1
  Find the cut-in setting on your water pump pressure switch. The setting is usually printed on the cover or back of the switch. The pre-charge air pressure in the water system tank must be between 2 to 4 pounds less than the cut-in setting. For example, if you have a 20 to 40-pound pressure switch, the cut-in setting is 20 pounds. The pre-charge setting should be between 16 to 18 pounds per square inch.
- 2
  Remove the cap from the air fill valve on top of the water system tank. The air fill valve is just like the air valve on a car tire.
- 3
  Attach an air compressor hose to the fill valve and begin filling the bladder bag with air. Stop periodically and check the air pressure with a standard pencil tire gauge. Continue filling until the air pressure is between 2 to 4 pounds per square inch less than the cut-in setting.
- 4
  Place the cap back onto the fill valve once the proper air pressure is in the bladder bag. Turn the well pump on and fill the water tank.

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