Install the well pump in accordance with the pump manufacturer's installation instructions. Test the pump and make sure the water being pumped out is clear of sand, silt or debris.
Turn the pump back off and finish running the water pipe into the house. A shut-off valve should be installed on the water line before the pressure tank so that the water can be easily turned off for maintenance or tank replacement.
If the tank being installed is a replacement tank, cut the water line to remove the old tank as close to the tank as possible. Install the male adapter or a short galvanized nipple to the elbow on the bottom of the new tank.
Most water pressure tanks have an elbow already installed by the manufacturer on the bottom of the tank. Wrap the threads with four layers of Teflon tape for a better seal.
Use two pipe wrenches to tighten the adapter or nipple. Place one wrench on the elbow and use the other to tighten the fitting.
Adjust the tank pressure on a diaphragm or bladder pressure tank to match the well pump pressure switch setting before installing the tank. Set the water tank pressure to 2 to 4 psi below the cut-in pressure setting at the pressure switch.
The cut-in setting is the point where the pump turns on automatically. A bicycle tire gauge can be used to check the water tank pressure.
If the pressure switch setting information is illegible, which is sometimes the case with older electronics installations, temporarily set the tank pressure to 27 pounds for an above ground pump and 37 pounds for a below ground pump and make adjustments after the tank is installed and the pump is running.
Complete the installation by attaching the pressure tank pipe to the water pipe. There will be a water line going into the pressure tank from the well to the elbow underneath the tank and then another water line from the tank to the rest of the house.
Turn on a faucet and watch the well pressure gauge to determine what the pressure reading is when the pump kicks on. Turn off the power to the pump and drain the pressure tank.
Check the bladder or diaphragm pressure. Adjust the water tank pressure to 2 to 4 pounds less than the cut-in pressure reading on the well pressure gauge if necessary.