In plumbing, there are often devices called backflow preventers installed in water entry rooms, and also prior to connection to appliances such as dishwashers. 

What are these devices, and why are they required? 

Here’s a quick primer on backflow devices, how they can prevent problems, and what you need to do to maintain them.

 

What is a backflow device?

A backflow device is a device that prevents the reversal of the normal direction of flow.  This scenario can happen when you have negative or supply pressure in the supply main. 

In the below example, if a line is in a submerged bowl or bucket, and a valve is open on a lower floor, it is possible to siphon the water from above to the open valve if the main supply is closed.
 

Why is it needed?

Without backflow devices, it’s possible for dirty water to enter back into your building, or even worse, the water mains.  This can lead to contamination of the entire water supply.
 
What is required by code? 

The adopted code in Canada is CSA-B64.10 “Manual for the Selection and Installation of Backflow Prevention Devices”.
 
Why does my city want something different from the code?

Different jurisdictions have different requirements. Unfortunately, there is no standardization between cities.  Often, a more stringent requirement than what is in CSA is required.
 
What maintenance is required?

The two most common types of backflow preventers are Reduced Pressure Backflow Assembly (RPBA) and Double Check Valve Assembly (DCVA). 

Both of these have ports that need to be tested once a year by a Certified Backflow Assembly Tester.  BC Comfort has several technicians with this certification.
 
I have an existing building;  why does the city require that I install backflow prevention devices now?

The code has become more stringent over the years;  building types that previously did not require backflow devices previously now have them as a requirement. 

Some cities conduct periodic inspections to ensure that waterlines stay safe.
 

For more information on how to optimise your building, contact our Design team today. 

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