GAC Company
Back Flow Testing.

Back Flow Certifcation and Repair

GAC Plumbing Company is Certified and Approved for Testing and Repair by Sonoma County and the following City's

  • Santa Rosa
  • Rohnert Park
  • Cotati
  • Penngrove
  • Kenwood


A backflow preventer is a device that's installed on your home's water pipes that allows water to flow in one direction but never in the opposite direction. Its sole job is to prevent drinking water from being contaminated due to backflow.

How does “backflow” happen in the first place?

When water enters your home from the main water supply line, it should only ever flow in one direction: into your home.

But sometimes, due to pressure changes in the pipes, that water can actually flow backwards and seep back into the main water supply line. 

For example, backflow can happen when there’s a break in the main water line or when a fire hydrant is opened for use. Because pressure is lost during these events, water is no longer being pushed forward into your home and will flow backwards into the city water lines.

And when this happens, backflow can contaminate the public drinking supply with:
  • Fertilizers/pesticides
  • Human waste
  • Chlorine from pools/spas
  • Soap from sinks/dishwashers/showers

And that’s where a backflow prevention system comes in handy. Let’s take a closer look at how a backflow prevention system works.

A backflow prevention system… prevents backflow

Backflow prevention systems are devices installed onto a pipe that only allow water to flow in one direction

Think of it as a one-way gate that allows water from the city’s public water supply to flow into your home’s piping but stops water if and when it ever tries to flow backwards into the main water supply. 

For a better idea of how backflow preventers work, take a look at this diagram.

How do I know if I need a backflow prevention system installed at my house?

First off, any Sonoma County resident who has an irrigation system or a well is required to install a backflow preventer at the water meter (because both systems are at risk of contamination due to backflow).

Live elsewhere? Or are you a Sonoma County resident without an irrigation system or well? If so, you’re probably wondering if you need a backflow prevention device installed at your home.

Well, we still recommend you have a backflow preventer installed anywhere incoming water and wastewater might be cross-connected

Newer homes may have built-in backflow preventers on certain water lines but in order to know for sure whether your home has proper backflow preventers set up, we suggest having a plumber inspect your home’s water system. They’ll install backflow preventers where it’s needed.

Need help from a Certified plumber?

Just contact us. We’ll send out a plumber to inspect your system and provide the solutions needed to keep your drinking water safe from contamination.

A backflow device is also known as an RPZ valve. RPZ stands for Reduced Pressure Zone. This device is installed onto your plumbing system to protect your drinking water and the city water supply from contaminants.

RPZ valves are required when a house or building is equipped with an irrigation system, fire suppression system, or a large boiler (hereinafter referred to as Systems). Contaminants can enter an irrigation system from fertilizer or pesticides that are sprayed onto lawns. In the case of a boiler or fire suppression system, water sits stagnant or trapped in these systems, which leads to a build-up of bacteria and increased mineral content from the piping system.

If there is a water leak in the house, house water service break, city water main break, hydrant flushing, or hydrant use due to a fire, the water pressure in the house or city water mains can drop lower than the water pressure in the Systems. This can cause water from the Systems to back-up into the drinking water supply. The next time you or a neighbor turns on a faucet for a drink of water, the water received could contain contaminants. Even small fluctuations in city water mains that occur due to uneven water use from one neighborhood to the next can cause drops in pressure large enough to cause a back-flow and therefore contamination to occur.

If a drop in city or building water pressure occurs, the RPZ valve will open up, dumping water out rather than allowing the potentially  contaminated water to back-flow into the water supply. For these reasons, California State Law requires the use of an RPZ as outlined in the State Plumbing code and California Environmental Protection Agency. All city governments must comply with these laws. The law not only requires the use of an RPZ device but that device must be tested once every year. Only a licensed plumber with a Cross Connection Certification License can test and certify the proper operation of an RPZ valve. Once the RPZ is tested, the certification paperwork is forwarded by the plumber to the city.

It should also be noted that no building, house or system that currently requires protection by an RPZ is “grandfathered” from not having the proper device installed.

Why Choose GAC Company to Repair Your Back Flow Device

We are Certified and Tested in ALL brands of BackFlow Values and Licensed to Repair and Test your RPZ or BackFlow Value. We have thousands of hours of experience repairing and Testing all types of Back Flow Devices.

GAC Company is Certified For Hospitals and ALL Public works building's at an  0.01 Test Standard. 

Call for a FREE estimate on Back Flow Certifcation and Repairs.

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