What is a Backflow Preventer?

The water in your home is received from a main water supply line, flowing inward so that water enters safely and uncontaminated. However, there are instances in which water can flow backwards due to a change in pressure, going back into municipal water lines and contaminating the water. A backflow preventer can prevent the water from flowing backwards, helping to prevent contaminants from entering the water supply source.

How Does a Backflow Preventer Work?

A backflow preventer is designed to allow the flow of water in one direction. The valve only opens in one direction, allowing clean water to flow into your main water supply line. If water were to flow in the opposite direction, the valve would close, preventing any backflow.

Types of Backflow Preventers

There are three main types of backflow preventers:

Double Check Valves

These devices are provided with two check valves to keep contaminants out of the clean water. If one valve sticks in an open position, the second check valve can be used to eliminate the negative effect of a change in water pressure. Double-check valves are often used in fire, lawn, and boiler systems.

Reduced Pressure Zones

Reduced pressure zones have two check valves. One key difference, however, is that reduced pressure zones also are equipped with a relief valve constructed to open and release contaminated water. If the relief valve is flushing water from the pipes, there may be damage to the main water supply pipes or check valves. Reduced pressure backflow preventers are common in cities and suburbs.

Pressure Vacuum Breakers

Pressure vacuum breakers are made for lawn systems. They prevent contaminated water in sprinkler systems from entering your clean water.

Signs of a Broken Backflow Preventer

Here are the most common indications that a backflow preventer may be damaged: 

Discolored Water

A broken backflow preventer in your pipes may result in discolored or cloudy water, which can cause health issues such as nausea and diarrhea. 

Water Leaks

A leak may begin once a backflow preventer malfunctions due to age and wear and tear. Leaks can cause damage such as mold and unpleasant odors.

Inspection of your backflow prevention device

According to La Régie du bâtiment du Québec (RBQ), building owners have the obligation to protect the drinking water system against contamination by installing a backflow prevention device and having it checked annually. However, this obligation excludes residential buildings with less than 9 units or less than 3 stories. If it is proven that the contamination originates from a building, the owner can be criminally prosecuted and will have to pay the costs of cleaning the system.

As a building owner, make sure to have your backflow preventer inspected every year by a certified inspector such as McHenry Plumbing.

If you are a homeowner and suspect that your backflow preventer may be defective, contact us. We offer plumbing repair services in Montreal and will be happy to help you.