what is backflow
Backflow is a term in plumbing for an unwanted flow of water in the reverse direction.It can be a serious health risk for the contamination of potable water supplies with foul water. In the most obvious case, a toilet flush cistern and its water supply must be isolated from the toilet bowl.ackflow occurs for one of two reasons, either back pressure or back siphonage. Back pressure is the result of a higher pressure in the system than in its supply, i.e. the system pressure has been increased by some means.