<P> A simple example is the space between a wall mounted faucet and the sink rim ( this space is the air gap ) . Water can easily flow from the faucet into the sink , but there is no way that water can flow from the sink into the faucet without modifying the system . This arrangement will prevent any contaminants in the sink from flowing into the potable water system by siphonage and is the least expensive form of backflow prevention . </P>
what does the air gap do on a dishwasher
backflow prevention