A byelaw kit should be installed as per the water regulations to allow for a type A-B air gap within the tank, this is designed to prevent the water within the tank every reaching the inlet and causing cross contamination with the water supply. this is especially important when the tank is being supplied with mains water and used a booster set.

The kit will include a warning pipe and overflow pipe to prevent the tank from overfilling. A screened breather for the tank to allow circulation of air.