A backflow preventer is a valve which will protect your drinking water from chemicals. Most people don't give a moment's thought to their drinking water. In the past, we might have walked miles to a well to collect water, but now we simply turn on the faucet and drink as much as we like. A serious problem can develop that springs from backflow. Water may come out of faucets, but under certain conditions, other things can also flow back up the pipe.
Different issues have been associated with backflow; some of them are lethal (many cases of poisoning and even explosions). The severity of these results warrants the installation of a backflow preventer in certain cases.
The main water supply has a certain pressure, and this is what causes water to come out of the pipe. So if something else is more powerful than the pressure of the main water supply, the foreign substance could quite easily force against it and enter the water supply.
For example, in Cincinnati, a wine brewery left their water faucet open after cleaning the tank with water. When the tank was used, the pressure was greater than in the main water supply. This resulted in wine flowing back up the water pipes and into people's houses.
Water was also used in a similar way to clean out a gasoline canister. The pressure in this canister was higher than the water main, and it resulted in three houses being blown up and destroyed because the gasoline entered their water supplies.
Siphoning can happen to anyone. This is when the pressure of the water supply drops very quickly. The lowered pressure will create a vacuum, which will ultimately mean that liquids can get sucked back up the pipe.
One time when backflow can be dangerous in most homes is with garden sprinklers. If you use an inground sprinkler, it could suffer from backflow. In that case, your water supply will be contaminated with fertilizers and whatever else you put on your lawn. Some states actually make the backflow preventer valves a legal requirement if you are fitting your home with a sprinkler.
Industry also needs to employ backflow preventer valves. If they use water for anything, they risk chemicals making their way into the water supply.
Installing a Backflow Preventer
A backflow preventer is very easy to install. If you want one for your garden sprinkler, you just screw the backflow preventer onto your hose.