Plumbing is never as simple as it looks, especially when you are doing it as part of your kitchen or bathroom remodeling project. The reason plumbing gets difficult for many DIYers is the presence of codes. If you don’t follow the rules or codes, then problems are bound to occur.


Every country and provinces has its own form of building and plumbing codes. These codes exist to protect people and their residences. As long as you follow the codes, any plumbing job should be of ideal quality, thus ensuring a safe environment. Other codes protect the consumer. However, they are all important.


Let’s have a look at some Canadian plumbing codes


Ontario Building Code: Plumbing and Drainage Systems

Before we get into very specific codes for plumbing, let’s have a look at what building codes from Ontario start about plumbing.


Firstly, section of the Ontario Building Code states that any building that abuts with a street where “a public or municipal water main is located shall be provided with or have accessible to its occupants a plumbing system.” The plumbing system includes drinkable (potable) water, plumbing fixtures, and a sanitary drainage system.


If a sanitary drainage system cannot be provided due to the absence of sanitary facilities, water supply, chemicals, or other means, then disposal of waste is provided.


Lastly, plumbing fixtures do not need to be provided in buildings that are not usually inhabited by people or where such fixtures would be considered impractical.


Core Codes

Common plumbing codes are ones that focus on venting, one of the overlooked elements of decent plumbing. When drain pipes are not vented correctly, fluids will drain sluggishly, and toxic fumes may be released into the house.


Here are some of the core codes to keep in mind:


  • Plumbing fixtures are not be placed on top of one another or packed too closely. This is especially important in the bathroom, where space is not always largely available.
  • Determine correct piping materials. Most inspectors accept copper piping for supply lines, while drain lines should be PVC.
  • Determine the correct sizing for supply lines, drains, and vents.
  • To get enough water pressure, you should replace an existing globe shutoff valve with a gate valve or full-bore ball. These two options do not impede water’s flow. If there is not enough pressure, you may require a booster pump. High water pressure requires a pressure-reducing valve instead.
  • Installing plumbing must never weaken the internal structure of the house. Inspectors may require you to reinforce any joints that were cut to accommodate the installation of pipes. Other requirements including placing protective places over some pipes and caulking around pipes.
  • Water hammer arresters may be needed for certain appliances. Supply lines sometimes need to be cushioned when they run through or near a framing member.


Aside from the above mentioned essential codes, there are some standard codes that are expected anywhere you go. For example, one code discusses that correct slope of drain pipes. It states that drain pipes must have at least a ¼ inch per running foot slope.


Another code mentions that, in order for inspectors to see which pipes have been primed or not, plumbers and DIYers are required to use purple primer.


Other codes make inspection and repairs much more easy to accomplish. For instance, the installation of cleanouts. Code dictates that cleanouts are needed at various places along pipes so that they can be easily cleaned and augered in the event of a leak or clog. Furthermore, cleanouts, compression pipes, fixture controls, and valves cannot be covered completely by flooring or walls, because you may need to work on them in the future. If necessary, access panels should be installed.


Important Plumbing Codes

Most codes set forth by the National Plumbing Code of Canada look at things like drainage fixtures, potable water, traps, and venting. Again, most of the “codes” are merely standards that ensure quality.


Here are some of the main points for potable water:


  • Thermal expansion tanks are not always required. If you want to check if you need one, seek out if your plumbing system has a check valve, PRV, or a backflow preventer.
  • Hot water tanks all require a vacuum breaker.
  • Storage type hot water tanks need a drain pan that is a minimum of 50 mm (2 inches) in diameter wider than the tank’s width. The drain pain side walls must also be around 25 mm (1 inch) tall.
  • The highest PSI someone is allowed to have for the water pipes in their home is 550 kPa or 80 PSI. If incoming pressure is more than that, the house will require a PRV to be installed.


Next, let’s have a look at codes about fixture drains. According to the National Plumbing Code of Canada, a fixture drain is a pipe connecting to a trap that serves a fixture to another section of the drainage system.


The standard lengths for running a fixture drain to another section of the drainage system are:


  • 6 feet for 1.5 inch piping
  • 8 feet for 2.0 inch piping
  • 12 feet for 3.0 inch piping


For water closets and similar, the fixture drain can be 10 feet (regardless of 3-4 inch piping).


What about traps? Do vents require traps and vice versa? The short answer is yes. Both dry and wet vents need traps. However, not even fixture requires a trap. There are some situations where floor drains can share traps. Also, indirectly connected fixtures do not need traps.



There are many plumbing codes around that can help you or a plumbing contractor do the job correctly. Knowing what plumbing codes are and how they can affect you, or what they are meant to do, ensures that projects are done properly. After all, one mistake is more than just costly—it can be a health concern or cause damage to your home!