How can water backflow into a home from something like a garden hose when the supply line into the house has constant positive pressure, and the hose is open ended?
In: 2
If there is a sudden change in pressure in the water supply line, this can cause water to backflow into the home. This could happen if there is a break in the line or if someone turns on a faucet elsewhere in the house, for example. If the hose is open ended, then this also creates a path for water to flow back into the house.
I think you’re asking in a roundabout way why backflow preventer devices are recommended for outdoor hose bibs. The reason, as far as I know, is that hoses aren’t always open ended. If you put a spray nozzle on the end it’s easy for that to become the way you shut off the flow of water, forgetting to also shut the bib. In that situation you wind up with stagnant water under pressure in the hose. If you open a tap in the house, suddenly the pressure inside the house is lower than it is in the hose, and the nasty water makes its way inside.
Latest Answers