What Is a Backflow Preventer?

You assume your drinking water is safe each time you turn on your tap, but backflow could allow contaminants into your home's water.

A backflow preventer can help with this situation.

The water that comes into your home should only flow in one direction. It comes in through the main plumbing line, runs through your pipes and flows out of your home after you've used it. Backflow refers to a change in water direction, and it can happen when there's a major change in water pressure, such as during a water main break. Instead of only flowing one direction through your home, it reverses directions and goes back the other way, potentially bringing with it lots of contaminants that enter the clean water coming from the main water line. This can include human waste, pool chemicals, soap, chemicals and fertilizer.

What Is a Backflow Preventer?

A backflow preventer is a simple valve installed on your home's plumbing pipes that blocks water from flowing back through the water system in the wrong direction. Businesses and multifamily dwellings typically must have backflow preventers installed. Most single-family homes don't require one unless you have a sprinkler system or pool, but it can be beneficial, even if it's not required.

The valve is designed to only allow water to flow one way. If the pressure reverses, the valve closes to keep the dirty water from flowing back into the clean water supply. This prevents clean drinking water from being contaminated if your water pressure changes significantly. The main benefit of installing a backflow preventer is keeping drinking water clean for your family and the community since backflow can enter the main water supply lines.