Ask the average homeowner how their backflow preventer is holding up and you're likely to be met with a quizzical, if not slightly upset look in return. Despite the importance of these plumbing system components, most folks just don't know they're even there!

First, let's look at what they do. This way you'll appreciate it that much more when you learn where to find one on your house.

The short and simple of it is that backflow preventers keep nasty, non-potable, water out of your home's plumbing system. Sources for this bad water are things like ponds, pools and puddles, which can be present in almost any residential environment.

Here's a common scenario:

You're washing the car with the garden-hose and happily going about your business. Let's say you're using the hose with no spray nozzle and multi-tasking by letting let the water run in the garden between rinses. You may not even take notice of the fact that a sizeable puddle of water has accumulated in the garden. The open end of the hose is in that water.

If you leave it this way and then go shut off the water, a backflow scenario can ensue. Sometimes a simple siphon situation can happen if the various elevations are suitable, but if someone inside happens to be using water at the same time, the system pressure can actually suck water forcefully from the puddle. That's not what you want to be making your pasta with, hence the need for a working backflow prevention device.

Often these devices are in the form of what's known as a vacuum breaker where the hose attaches to the spigot (aka hose-bib), but there are a number of types.

Irrigation systems also require backflow prevention devices. It's very common for an irrigation pipe to get a small crack that doesn't present an immediate concern, but it allows some contaminants into the water supply system.

Backflow Preventer Testing

It's clear that working backflow preventers are essential for the safety of your drinking water supply. But how can you know that yours is working as it should?

The answer is simple: testing. Backflow preventers should be tested periodically to ensure that all functions are working properly. Often, older vacuum breakers have been damaged or have simply exhausted their service life and require replacement.

Both the testing and any replacement parts are relatively inexpensive – a small price to pay for the assurance of quality water.