[Answer] Backflow is when water...?

Answer: reducing pathogens to safe levels

Most relevant text from all around the web:

Backflow is when water...? What is Backflow Prevention and Cross-Connection Control? Backflow - Wikipedia Backflow prevention device - Wikipedia Backflow prevention device - Wikipedia 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. For this reason building codes mandate a series of measures and backflow prevention devices to prevent 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. For this reason building codes mandate a series of measures and backflow prevention devices to prevent backflow. Backflow 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. This may occur in unvented heating systems where thermal expansion increases the pressure. Backflow 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. This may occur in unvented heating systems where thermal expansion increases the pressure. Back siphonage is the result of supply pressure being lowered below that of the system. This may occur when a supply is interrupted or drained down. Backflow within the context of the drinking water industry means the reversal of water flow from its normal or intended direction of flow . Whenever a water utility connects a customer to its water distribution system the intention is for the water to flow from the distribution system to the customer. However it is possible and quite common for the flow to be reversed and flow from the customer’s … Backflow is the unwanted flow of water or other liquids mixtures gasses or substances into the drinking water supply . There are two main ways backflow can occur: Backsiphonage occur...

Disclaimer: 

Our tool is still learning and trying its best to find the correct answer to your question. Now its your turn, "The more we share The more we have". Comment any other details to improve the description, we will update answer while you visit us next time...Kindly check our comments section, Sometimes our tool may wrong but not our users.

Are We Wrong To Think We're Right? Then Give Right Answer Below As Comment