What Are Backflow Prevention Devices Used For?

A backflow preventer is a device that is critical to keeping our drinking water safe. Simply put, it keeps potable water from mixing with contaminated water. One of the ways it can occur when backpressure can cause this to happen. That’s when there is a higher pressure existing in the downstream piping system than in the supply piping. This allows downstream substances to be pushed back into the potable water supply. Some of the most common causes include pumps, thermal expansion, and elevation.
The other way backflow occurs is when there is a back siphon. A back siphon happens when there is a negative pressure in the supply piping that allows downstream substances to reverse direction and be pulled back into the potable water supply. A water main break can cause this to happen.
But if a backflow prevention device is installed in a utility vault and the utility vault floods, the drinking water can become contaminated. The test cocks on the backflow preventer can open and allow the contaminated water in.
When contaminated water mixes with potable water it’s called a cross-connection. A backflow prevention device keeps a cross-connection from occurring.
This video provides a brief overview of cross-connection control within our public water supply. It also definitely answers the questions What is backflow? Why is backflow prevention is needed? And what standards the waterworks industry provides to keep it from happening?
See our other videos for more on backflow prevention and cross-connection and why installing your backflow prevention device outside and above ground, in a backflow enclosure is the safest, most cost-effective way to go.
For more information visit: www.safe-t-cover.com/

[@mromneyobama]

But the underground water supply are inside pipes so even if fertilizers seep from above ground to underground, they won't contaminate the water because water is shielded by metal or PVC pipes. What am I missing?

[@arlflors6273]

Obama

[@Chrominance87]

It is possible for contaminants to be backsiphoned into the potable water system through cross connections. A common example would be a watermain break causing a massive drop in pressure. This drop in pressure can cause the water in a nearby home to reverse direction. If the end of a garden hose is in a bucket of paint, that buckets contents will be siphoned into the water supply.