Canadian Underwriter

Different interpretations of codes impacting installation of backwater valves

February 15, 2013  

Print this page

A new study by the Institute of Catastrophic Loss Reduction (ICLR) has found that municipalities across Canada are interpreting national building and plumbing codes governing the installation of backwater valves in different ways.

As a result, some areas of the country have much lower installation rates than others, putting homes at greater risk from urban flood damage.

Read: Is it time to revisit flood coverage?

Urban flood damages are a recurrent and growing issue for municipalities, insurers and homeowners across Canada. Damages from urban flood events often total in the hundreds of millions of dollars.

Previous ICLR research has found that a mainline, full port, normally open backwater valve, when properly installed and maintained, in tandem with the severance of foundation drains (i.e. weeping tile) from the sanitary sewer, is one of the best measures a homeowner can take to reduce the risk of stormwater and/or sewage backing up into a basement.

Read: 6 tips to protect your home from water damage

But building code/plumbing code and/or local by-law requirements to install such valves in new homes is spotty across the country, largely owing to code interpretation, says the ICLR.

The study revealed that backwater valve building/plumbing code wordings are interpreted differently across the country, though there is greater interpretation consistency in some regions than in others. Specifically, the survey found that 19% of British Columbia respondents, 81% of Alberta respondents, 86% of Saskatchewan respondents, 72% of Manitoba respondents, 26% of Ontario respondents and 58% of respondents from New Brunswick and Nova Scotia interpreted code wordings in a manner that required backwater valves to be installed in all or most new homes. The study further revealed that interpreting code wordings in this manner was strongly correlated with a higher frequency of installation of backwater valves in new homes, indicating the importance of code interpretation for backwater valve installation.

Read: Rain barrels can help reduce home water damage

According to Dan Sandink, study author, “Despite the fact that the National Building Code of Canada and virtually all provinces use near identical code wordings in the backwater valve sections of their respective building and/or plumbing codes, this study found that there are differing interpretations of code wordings, resulting in differing frequencies of installation of backwater valves. So, while building and plumbing officials in many jurisdictions in Canada interpret the code as meaning that all new homes should have backwater valves, some officials in some jurisdictions interpret the code as meaning that backwater valves shall be used only in certain circumstances.”

The primary recommendation of this report is that sentences in the National Plumbing Code and provincial building and/or plumbing codes that relate to installation of backwater valves to protect against sewer backflow be reworded or clarified to ensure they are clearly and consistently interpreted and applied.

The study can be downloaded at

This story was originally published by Canadian Insurance Top Broker.