Cross Connection
A physical or potential connection or arrangement between two otherwise separate piping systems, one of which contains potable water and the other water of questionable or unknown safety. This occurs when the water pipe to the property is connected to, or in contact with, something other than potable water. During a backflow condition any substance that may be in contact with the water supply that is within the property piping could be drawn back into the water distribution system. This could contaminate the main water supply if the pipe is connected to any industrial chemical, gas, or waste material.
Cross Connections typically happen when hoses are submerged in places such as buckets, tubs, or sinks, or attached to waterbeds or spray containers.