Begin by attaching the hose to the tap on the water tank and opening the valve. Turn the water on and wait for your water tank to fill. Once full, water will exit out of the top of the water tank at the breather, turn filling tap off immediately, failing to do so can over pressurize your tank and cause damage.

Once full, turn off the water. Close the valve and remove the hose. Your water tank is now full. This process works for both under tray water tanks and head board water tanks.