Basement Drain Backing Up When Flushing Toilet

Basement Drain Backing Up When Flushing Toilet

Basement Drain Backing Up When Flushing Toilet

basement drain backing up when flushing toilet

Sewage can back up into your home when either your home’s drain pipes or main sewer line becomes clogged. For example, if one toilet creates a sewage backup, the drain connected to that toilet will likely be clogged. But if all toilets or bathtubs in your home create backflows, then there may be a clog in the main sewer line or the sump pump failed. Clogs can consist of hair, grease, or other solid materials that end up in the drains.

If your basement floor drain backs up when the toilet is flushed, it’s caused by a blockage in your home’s sewer line. The most common source of these blockages is flushing items that aren’t meant to be flushed, but tree roots invading the sewer line can also cause blockages. This is not a DIY fix. 

Generally, abuse is something like flushing more materials (or the wrong items) than your main drain line can handle. It’s the most common cause of floor drain backups. Here are some tips to avoid an unexpected clog:

  • Be careful about what you flush down your toilets. Toilet paper and most non-corrosive liquids are okay. But never flush paper towels, baby wipes, and feminine hygiene products. They’re simply too thick to dissolve thoroughly and flow through your pipes.
  • Make sure little ones don’t play in the toilet (hey, we’ve all been there with our kids!). They’ll often dump toys and other plastic items into the toilet bowl and flush.
  • Ironically, of the most common causes of floor drain and toilet drain backups, toilet paper is the number one culprit of clogged drains.
  • Certain toilet papers are better than others and we strongly encourage you to choose your brand wisely. It can save you thousands of dollars down the road.

Floor Drain Backup – Causes

Usually, backflow in your basement floor drain is caused by non-flushable items sent down the toilet. Even if they make it down the toilet successfully, they often clog the main sewer line between your home and the city’s sewer system. 

It’s extremely important to only flush toilet paper and human waste down your toilet. 

These are a few examples of commonly flush items that should never be flushed:

  • Paper Towels
  • Facial Tissues
  • Pads & Tampons
  • “Flushable” Wipes – These are NOT FLUSHABLE. No matter how much the labeling says they are, these do not break down like toilet paper and can cause serious blockages.
  • Prescription Medication – This one won’t cause blockages, but you still shouldn’t do it. It can pollute the water and impact the wildlife. Call your local pharmacies to find one with a drop-off bin for unused medication.

This list is far from exhaustive. Unfortunately, many people use their toilets as an extra waste basket. Sewage systems are only designed to handle raw sewage and toilet paper – and if there’s a blockage, that sewage is coming back up the floor drain.

Blockages aren’t always your fault, though.

As disgusting as it may be, raw sewage is full of nutrients. Trees love it and their roots will seek out the moist sewer line, looking for any entrance. Once they’re inside, they just continue to grow – eventually catching hold of toilet paper and normal sewage until the pipe and drain are completely blocked. 

Preventing Further Floor Drain Backup

The main water line is where all the water flows into your home from your city’s water supply. Where the sewage line is the Out, the main water line is the In.

The sewer line connects all the drains in your house to the sewer system – it can get messy when it’s blocked. If someone is trying to take a shower or flushes the toilet, the basement floor drain is the lowest unblocked point of exit.

To turn off your water supply, you need to locate the shut-off valve. It should be inside your home, usually around the perimeter on the street side. If it’s proving difficult to find, the property inspection report that was completed when you purchased the house should have the location listed.

Alternatively, call your local water company. The main water line has another shut-off valve at the street level. Sometimes you can turn it off yourself, but other times it requires an emergency dispatch team from the company. 

Locate The Sewer Cleanout Pipe

Plumbers will need to access this pipe to unclog the sewer line. By preemptively finding it, you can save time that the plumber might charge for. 

The sewer cleanout pipe is usually in the backyard, but in colder climates it may be inside the home or garage. To find yours, walk around your house looking for a pipe jutting straight upwards. Usually, these are white or black PVC.

Since it isn’t used often, it may not be immediately apparent. Check under bushes and other overgrowth that may be covering it.

In colder climates, the sewer cleanout line may be located indoors. In these cases, it will usually be a good distance away from living spaces – garage, basement, and utility closets are all common.

Once you’ve located yours, remove the cap if possible. This should relieve some pressure in the sewer line. 

Call A Plumber

As we said before – this is NOT a DIY fix. A plumber has the tools and knowledge needed to unclog your sewer line safely. They use a relatively simple process.

Using the sewer cleanout pipe, they thread a camera on a snake into the piping to locate and identify the blockage. If it’s a minor blockage, caused by thick or large amounts of toilet paper, a plumbing snake is usually sufficient to unclog it.

A hydrojet is the solution for more serious blockages. This high pressure water jet can cut through most non-flushable items, but must be used with care to prevent damage to the pipes.

What A Plumber Might Do

If the blockage is caused by root systems invading the sewer line, they may use specialized chemicals to kill the root systems. This can be the most expensive issue, with severe cases requiring the replacement of pipes.

While it is possible to buy these tools as a consumer, we don’t recommend you trying to tackle this problem yourself. Misusing these tools can cause damage to your sewer line, which can end up being way more costly.

When speaking with the plumber, inquire about the cost of installing a backwater valve in your basement floor drain. A backwater valve will seal the drain when sewage begins to back up, preventing a messy cleanup.

Cleaning Up After Your Basement Drain Backs Up

The basement floor drain blockage has been removed – and now it’s time for the cleanup. If it was a serious flooding event that flowed up the walls, there may be hidden electrical damage. In these cases, consult a professional cleaning crew to avoid unnecessary risk.

If it’s a small flood that didn’t reach walls with running electricity, it should be safe to clean it up yourself. Wear clothing that you are okay with getting rid of, as well as goggles, a facemask, and gloves.

We have described all the steps in detail in this article:


Best Toilet Paper to Prevent a Basement Floor Drain Backup

  • Scott 1-Ply bath tissue is best for dissolving more efficiently and thoroughly in water. This makes your pipes less vulnerable to clogs.
  • If you absolutely need more cushion from your toilet paper, try Angel Soft 2-Ply bath tissue. Not quite as good as the Scott but it’s much better than most.
  • 100% recycled toilet paper is probably the most dissolvable bath tissue and therefore the safest for your pipes. If you don’t mind spending a bit more per sheet to help with the environment, then a brand like Seventh Generation is your best bet.
  • We do not recommend brands like Quilted Northern Ultra Plush or Cottonelle Ultra Comfort Care. These 2-Ply toilet papers do not dissolve well in water.
  • KEEP IN MIND: 1-Ply bath tissues will prevent clogging issues better than 2-Ply bath tissues. However, it’s up to you on how to balance your clogging issues with the usually better comfort provided by a 2-Ply bath tissue.

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BY M. Kogan

Hello, I am Marcio. I am an architect and designer, alma mater is Mackenzie. Retired in theory, but an architect never retires completely. Along with architectural projects, I am a filmmaker and have completed some short documentaries. Filmmaking and design are my passions. In HomeQN I write about home decoration and foundations. The goal is to teach homeowners to DYI as much as possible, and when this is not possible, enable them through knowledge, to evaluate service quotations and choose the best service technicians.

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