Backflow into a public water system can pollute or contaminate the water in that system (i.e., backflow into a public water system can make the water in that system unusable or unsafe to drink).  Each water supplier has a responsibility to provide water that is safe to drink.  Consumers have confidence that water delivered to them through a public water system is safe to drink.  In the best interest of its customers, each water supplier must take reasonable precautions to protect its public water system against backflow and back-siphonage.