Often, homeowners like to leave the basement well enough alone. Whatever goes on down there is a mystery, since it’s outside your field of view, so rather than meddle you just let it do its thing. But unfortunately, basements are not self-regulating, and even though there might not be a clear and visible issue, you might still need to get your drain inspected or replaced.
This is certainly true of the basement floor drain. Your house won’t flood, and your pipes won’t spring a massive leak when there’s an issue with the drain, but you will be greeted with a foul, sewer odour, enough to make any homeowner gag. But rather than cancel your dinner party plans out of embarrassment, just call in the pros.
Keep Your Home Up-to-Code, Or Beyond
Although not all homes have one (or the one they do have is old and non-functional), Ontario plumbing codes define mandatory floor drain installation in the basement furnace room. When we discuss the role of a floor drain a little later on, it will become clear why they have been made mandatory, but suffice it to say for now that a floor drain expels unwanted water and protects against unwanted gases.
Some houses have more than one floor drain, but that is optional. For example, some homeowners prefer to have an additional floor drain in their laundry room. When you think about it, your washing machine holds around 150 litres of water, and if the drain line from your washing machine fails, that amount of liquid can cause major damage. Rather than contend with a mess of wet drywall, and can pay to just proactively install a second floor drain.
Luckily floor drains are mostly uniform and standardized. Because the main drain is a 4” pipe, most floor drains have the same size. This means that installation isn’t all that tricky.
What Is a Floor Drain?
You might be wondering, though: what is a floor drain, exactly? A floor drain is a roughly U-shaped fitting that is connected to a drain branch, which leads to the main drainpipe. In other words, it is a P-trap (a sloped, curved pipe that collects debris and prevents back flow into the house) where water sits pretty much all the time.
What Function Does It Serve?
This water sitting in the P-trap creates a barrier, and prevents sewer gases from entering into your living space. Whereas an empty pipe would let in noxious gases from the sewer system, the floor drain’s liquid stops it. Put this way, it’s easy to see that the floor drain actually plays a crucial role in plumbing safety.
This means, unfortunately, that a problem with the floor drain opens your home up to some seriously unpleasant smells. If an old clay P-trap has a crack, water escapes from it, seeping to the lower level into the soil, which causes an awful, noxious smell to permeate.

When Problems Arise…
In the picture above, you can see an old floor drain that is made of clay. Because of some cracks at the bottom, the water couldn’t hold inside the pipe, and leaked out. The homeowners complained about a foul smell in the basement, and sought Mister Plumber’s drain cleaning services in Toronto to help sort out the smell. The only weird thing, they noted, was that the smell was on and off – it wasn’t a lingering, always-present odour.
There’s actually a pretty simple explanation for that: if atmospheric pressure is high, the foul odours aren’t drawn into the home from the pipe. As soon as the pressure goes down, though, that distinctive sewer smell comes up from the drain. If you catch any odd whiffs coming from the basement, any sewage-y smells at all, it is best to tackle the problem immediately. You can peruse our guide to drain repair and replacement or, better yet, give us a call.
Mister Plumber is available 24/7 for emergency plumbing cases, with loads of experience working with drains.
Consider Replacing Your Old Floor Drain
Old floor drains can be replaced with newer PVC pipes, which are less likely to crack and cause problems than their clay counterparts. All the connections for the pipe and its fittings are glued, so water will never escape the P-trap, and your home will never be bombarded by sewer smells.
Over time, as strides were made (and continue to be made) in the field of plumbing, the plumbing codes have changed. The current one requires the installation of a so-called “primer tube” that supplies a small amount of water to the floor drain to make sure it doesn’t dry out. (Please note here that the tube from the furnace, which discharges condensed water, is not enough lubrication for the pipe).
In the plumbing codebook, there is a lot of information about floor drain installation and proper venting. Mister Plumber is an expert in both underground and above ground drain systems installation, so we’re uniquely suited to help you fortify your floor drains, and ensure your basement plumbing is working in tip-top, fresh-smelling order.

To Recap…
Although your basement is “out of sight, out of mind” sometimes, you shouldn’t neglect issues that arise from it. One such common issue is a problem with the floor drain, a drain whose installation has been made mandatory by the Ontario codebook. Floor drains prevent the backflow of noxious gases into your home using a P-trap, a curved pipe that collects standing water even when there is no flow. That water creates a barrier against the gases.
If your P-trap is clay, as many are, it is susceptible to cracks, which cause the protective barrier of water to seep out. When atmospheric pressure is low, those gases start permeating your residence, spreading stinky gas everywhere. The best defense against these gross odours is a newly installed PVC floor drain, which is far less likely to crack, and which is held together at joints by reliable glue. If you smell something, call someone! Call Mister Plumber immediately and we’ll help return your home to its fresh-smelling self.