What is a backflow and how can it be prevented?
a) Backflow is the reverse flow of contaminated water; it can be prevented by installing backflow prevention devices
b) Backflow is the overflow of clean water; it can be prevented by regulating water pressure
c) Backflow is the release of steam from a boiler; it can be prevented by regular maintenance
d) Backflow is the buildup of sediment in pipes; it can be prevented by flushing the pipes regularly