A double check backflow preventer is a system which uses two check valves to prevent back flow from happening.

Why two check valves?

It is a fail-safe principle, more than anything else. The operating theory is if one valve fails, the other one will remain functional. A secondary value is that when one check valve closes, there is a corresponding drop in water pressure, which helps to seal tightly the second check valve plumbing.

When to use a double check backflow preventer?

Double check backflow preventers are usually used on irrigation systems. They are not adequate for larger systems, however, so if you have doubts about which backflow preventer is required for your property, get in touch with your local city’s water department and ask about requirements for your particular property.

What happens during a backflow inspection?  Generally a backflow service company will follow the same guidelines we follow at City Backflow Testing.

We use USC 10^th Addition Testing Procedures:

• Notify- Notify the customer we are here for testing
• Identify- Make sure serial number is correct and that we have the right assembly
• Inspect- Make sure there are 4 test ports and 2 Shut off handles
• Observe- Attach test equipment and follow proper testing  procedures  for this assembly
• Test Reports- Enter values for the  assemblies
• Turn in all test Reports to the local water Purveyor or City

 

Those are pretty standard steps taken by certified backflow testing companies.

Who is certified to inspect your double check backflow preventer?

Your city will have a list of companies which are licensed, certified, and approved by their water department to do testing, repairs, and backflow installation.

What is backflow?

Backflow is the reversal of water flow in your water system.  Instead of potable water flowing to your business, a sudden drop in water pressure can cause contaminated water to reverse flow and flow from your business or residence back to the city’s water supply.  Obviously this would be a huge health risk and thus the inspections are needed.

Does backflow happen often?

The answer to that question is this: probably more often than you would like to know.  Every time there is a fire in your city, and a fire hydrant is used, there is a resulting drop in water pressure throughout the water system.  Every time a water main bursts there is a drop in water pressure. If a water pipe develops a leak, or is punctured, backflow can occur, or if a business accidently leaves an industrial-sized faucet open and running, water pressure in the system can drop.

All require a backflow preventer to be in place to prevent against the health dangers of backflow.

We are City Backflow Testing and we would be happy to answer all of your questions about double check backflow preventer and backflow in general. Give us a call at (817) 996-2000 and ask your questions, and if you are in the Fort Worth area, give us a call for an estimate for a backflow inspection, repair, or installation.  We are here to help in the fight against backflow.