There is nothing more alarming, inconvenient, and disruptive than dealing with a problematic basement drain. The chances are that the wastewater backs up when it’s supposed to drain it, and the last thing you will want to happen is to deal with a flooded basement!

Keep in mind that the basement floor drain is one of your plumbing system’s most vital parts. As it sits on the lowest part of your house, it’s supposed to serve as an outlet for any unwanted water. Whether coming from heavy rain, HVAC unit condensation, or a leaking water heater, this wastewater should be properly drained away from your home.

If you’re wondering why your basement drain continues to back up, here are the five common reasons you must keep an eye out for and how you can address the plumbing issue:

1) Clogged Washtub Basin

Your washtub basin, also known as the laundry tub, can be the biggest culprit of a drain backup. When faced with this problem, all it takes is a quick fix by cleaning the strainer on the inlet. But the chances are that the trap under the basin is also clogged, which is causing the said problem. In this situation, you can use a plunger or snake to clear the sediment and debris. If the blockage isn’t accessible, get in touch with a professional plumber to handle the issue.

2) Floor Drain Blockage

Know that the floor drain that is connected to the house drain located under your basement is meant to drain excess water. However, the problem starts when clogs appear due to excess water in your basement. That said, be sure to get rid of the clog in the drain, the house trap, or the sewer main, so that drain backup is avoided.

3) Random Removal of the Main House Trap

For the uninitiated, the main house trap is a fixture in the main drain line, preventing sewer gases from getting into your home. As this system has a plug on the house-end and the street side, be sure not to remove them as wastewater may possibly enter your home. The best course of action is to open the one in the street-side, then the house-end plug, as doing so allows the wastewater to drain out of your home instead of the other way around!

4) Blockage in the Washing Machine

Another potential reason for your basement drain to back up is the washing machine. At times, this appliance experiences backups as it loads a high volume of water. To fix this, all you have to do is turn it off, check the strainer, and clear any blockage. If it still doesn’t work, ask for a plumbing repair from our professionals at Capital Plumbing and Heating to eliminate the blockage in the trap or further down the drain.

5) Low Plumbing Fixtures

If you’re wondering why your basement drain backs up, your low plumbing fixtures are likely the culprit, where it causes a backup in the showers, bathtubs or toilets in your basement. If the pipes were incorrectly installed previously, you should hire an expert to ensure your plumbing fixtures are a little high to eliminate possible causes of drain issues!


At this point, you now know five common reasons your basement drain is backing up. As outlined above, this plumbing issue can be caused by clogged wash tub basin, floor drain blockage, the main house trap removal, blockage in the washing machine, and low plumbing fixtures. By knowing where the plumbing problem comes from, the expert plumber will help ensure that you won’t have to deal with a basement drain back up ever again!

We provide plumbing and heating services in Edmonton and the surrounding areas, from sewer drain cleaning to furnace replacement down to water heater repair. If your basement drain keeps on backing up, get in touch with us today to see how we can help!