There are many ways air gets into the water supply as it travels though the pipes from your water supplier. Although water providers try to prevent outside air infusion, air is drawn into the water line in many ways such as during common main line breakages, pumps along the water line, small cracks or damaged joint seals and changes in temperature.
Most water meters measure volume passing through the meter so you are billed for the volume of water plus the air. The Flosaver Air Reduction & Efficiency Valve compresses the air in the pipe as it goes through the meter so you are billed only for water, not water plus air bubbles. This results in up to 15% reduction in water costs.