You Hold The Power

The last time the word “backflow” occupied my thoughts was in the early to mid-1980s when I was completing my plumbing apprenticeship. Around that time there were code changes relating to backflow. From my perspective the most significant of those was the requirement that vacuum breakers be installed on outdoor hose connections.

Since then there have been some changes making “premise” backflow mandatory in many cases. Premise protection means that not only do individual appliances such as boilers need to have backflow protection, but the buildings in which they are installed also need a backflow device installed at the point of entry to the building. An apartment building which previously had just an inexpensive dual check valve on the ½” water line to the boiler, may now need a larger, and much more expensive full-sized device on the main water line entering the building.

The first and best method of preventing any type of backflow is by way of an air gap. The most obvious example of an air gap is the spout on your bathtub. The tub spout terminates above the flood level of the bathtub so that it would not be possible, even in a negative pressure situation, for the dirty, contaminated bath water to re-enter the potable system by way of the spout.

Where air gaps are not possible or practical, mechanical backflow devices are necessary. There are three major types; the aforementioned vacuum breaker (VB), the dual or double check valve assembly (DCVA) and the Reduced Pressure Principle (RP). There are several versions of each of these types suitable for the varying installations, fixtures and risk factors.

It seems quite straightforward. Municipalities deliver safe clean potable water to homes, businesses and industry. We need to ensure that in the event of a backflow situation, the safe, clean potable water remains that way.

WHAT IS “BACKFLOW”?

When we refer to backflow, we are talking about the reversal of the normal direction of flow in a potable water distribution system. There are two types of backflow: back-siphon, and backpressure. Back-siphon is caused by negative pressure in the supply piping, possibly as a result of a water main break or due to high water withdrawal rate such as fire fighting or water main flushing. This is exactly the type of backflow that those hose connection vacuum breakers are intended to prevent.

Backpressure is caused whenever a potable system is connected to a non potable supply operating under a higher pressure such as a boiler, a high pressure car wash or perhaps a chemical feed system in an industrial plant. In these situations some type of backflow prevention device needs to be installed and maintained at the point of cross connection in order to protect the potable system from contamination.

When I was in trade school it seemed to me that putting vacuum breakers on every single hose connection was overkill.  In order for a hose to contaminate the potable system, the scenario would need to go something like this: on a nice sunny summer day, my neighbour Jack is spraying herbicide on his lawn using one of those sprayers attached to the garden hose. His wife calls him in and Jack puts down the hose, but leaves the tap turned on, and goes inside. While he is inside, the water main ruptures down the street. This causes a negative pressure in the line connected to Jack’s hose, which siphons the herbicide from the sprayer, down the hose and all the way back to the water main.

I arrive home shortly after the water main has been repaired and go to the kitchen tap for a drink of water. Just my luck, I get the water that has been polluted by Jack’s herbicide. My wife is left a widow, my kids fatherless. Not a good result, a couple of my neighbours might be happy to see me gone, but killing people is not what we want to do with our potable water.

There are hundreds of millions of hoses connected to potable systems all over North America. This kind of occurrence, although rare, can and does happen. Fortunately for all of us, I am not the one who decides the whos, whats and wherefores of public safety. There are organizations along with several layers of legislation, agencies and guidelines to ensure that the appropriate devices are installed and proper procedures are followed.

Probably the most authoritative resource on water safety is the American Water Works Association (AWWA), an international nonprofit and educational society and the largest and oldest organization of water professionals in the world. Its more than 60 000 members include more than 4600 utilities that supply water to roughly 180 million people in North America.

It is organized regionally into sections. The Canadian Section was founded in 1916  and has since evolved into five sections covering the country: Atlantic Canada (ACWWA), Quebec (QWWA), Ontario (OWWA), Western Canada (WCWWA) and British Columbia (BCWWA). The western section includes the Territories as well as Alberta, Manitoba and Saskatchewan.

The Canadian Standards Association (CSA) has developed the technical standard for the manufacture of backflow devices, as well as the testing and selection procedures for these devices. There are other guidelines, including the AWWA Cross Connection Control Manual, but the CSA B64. 10 is the current standard for the industry.

The B64 outlines the where and when backflow devices are required, charts out the three risk levels: minor, moderate and severe. It prescribes which type of device is required to obtain the adequate protection. The B64 also outlines where it is necessary to install a testable backflow device.

Testable backflow devices have test ports, which enable a trained technician with the appropriate equipment to test a device to ensure it functions properly. In order to protect the potable system, these devices need to be verified to be in working order at least annually. Testing must be carried out by a certified Cross Connection Control Specialist (CCCS).

It is the responsibility of municipalities to draft and enforce bylaws to ensure the safety of potable water systems. Most provinces have toughened up safe water legislation giving the municipalities the legislative clout they need to do so. Many municipalities in Ontario have recently done just that, which has led to the increased attention to the issues of backflow.

In trade school, we were encouraged to get our backflow tester certificates because it would be a lucrative business. Here in Ontario at least, that was not the case as enforcement of backflow testing seemed to be lacking. Now at last, it appears municipalities are serious about enforcing backflow bylaws.

If you got your certification back when I did, you will likely have to re-certify as AWWA certification is now the standard. Training and testing is still handled through the community colleges, but the certification must be AWWA (or the regional section such as OWWA in Ontario). Call your local community college for availability, classes fill quickly.

I know one contractor who flew from Ontario to Alberta to take a weekend certification course to obtain his certificate. He did this so he could service one of his larger customers who neede
d to meet the deadlines for compliance that their municipality had set.

So there we have it, quite a convoluted trail to ensure a safe glass of water. Many people I have talked to have thrown up their hands in frustration wondering who the ultimate authority in these matters is. Is it the AWWA, the municipality, or CSA? The truth is that the person with the most authority in these matters is the properly trained journeyman or Master plumber. A plumber with his CCCS certification is the only professional who can properly and legally survey a building for risk, install backflow devices, repair backflow devices and test backflow devices in every type of installation. No other professional, even a professional engineer with his CCCS, can perform all of these services.

If you have not already considered it, look into the opportunities and see if it makes good sense for your business. <>