Toilet Backing Up – It Flushes But Waste Comes Back | Fix It

Without meaning to, we all take our toilets for granted. We use them, they carry our waste away, and all is right with the world. 

Until it isn’t. 

There are few things more frustrating than flushing a toilet only to discover that its contents didn’t flow away, but instead, are still staring you in the eye. 

This is a common problem with many potential causes, and I’m going to assume that since you’re reading this article, you are looking for some help to resolve this very issue. Let’s get to it!

Toilet Flushes But Waste Comes Back?

You flush your toilet, everything appears normal, and then the waste you just flushed comes back.


If your toilet flushes but waste comes back, you’ve got yourself a sewer issue that many homeowners experience. The problem could be with the toilet itself, but more likely it is with a sewer line somewhere. The solution is simpler than you think, so keep reading to find out why your toilet is backing up and what you can do to fix it. 

Reasons Your Toilet Is Backing Up

As I mentioned earlier, there are several potential causes for why your toilet backs up when you flush it. Once you’ve identified the reason, you’ll be able to choose a solution to fix the problem, often without the help of a licensed professional. 

Not Enough Water In Tank

This is a common reason for toilet backup, especially since the invention of the low-flow toilet back in the 1990s. The fact is that sometimes these toilets lack the power it takes to fully flush the bowl’s contents. Luckily, if yours is a low-flow toilet and there’s not enough water in the tank to get the job done, there are a few tricks you can try to remedy the issue. 

First, adjust the float valve in the tank to allow more water to fill with each flush. 

Next, check the chain length on the flapper. If it’s too loose, it might be allowing the flapper to close too soon, thus restricting the water flow. 

Finally, use a drain cleaner or lime remover to clean the toilet. Sometimes sediment buildup can restrict the water flow in low-flow models. 

Blocked Drain Pipes

If the toilet itself is not clogged, the problem could be in the drainpipe that leads from the toilet to outside your home. Unfortunately, if your toilet flushes but backs up, for this reason, you probably won’t be able to fix it yourself. You’ll need a professional with the right equipment to reach that far into your home’s sewer system. 

You can, however, see if this is the problem by flushing your toilet and then paying close attention to the other drains in the bathroom. If the water bubbles up into the sink or tub when you flush the toilet, you are likely dealing with a blocked drainpipe. 

Household Object Drop Into the Toilet

If you have kids or pets, the blockage may be caused by a flushed toy. You’d be surprised at the number of toilet backup issues caused by little ones who find it fascinating to watch their (or the dog’s) toys take a swim in the toilet bowl. 

Cooking Fat Or Grease Build Up

Your mom may have done it because her mother taught her to, but if you’re pouring hot grease, oil, or fat down the drains in your home, stop right now. When these fats cool, they solidify and/or get gummy, causing a buildup of anything and everything that passes thereafter. 

Toilet Wipes Or Sanitary Products

There is a reason stores and other public places have signs in their bathrooms telling you to “Please do not flush sanitary napkins down the toilet.” It’s because these items do not break down in the sewer lines and will eventually create a massive clog that’s difficult to remove. 

The same goes for “flushable” wipes. Sure, they are flushable – they go down just like toilet paper. Unfortunately, they don’t break down like toilet paper, and over time, will clog the drainpipes in your home. The “flushable” in flushable wipes is just that: flushable, not dissolvable

Problems With Main Pipeline

Sometimes, circumstances beyond your control can cause your home’s toilets to back up. This usually has to do with the landscape and vegetation surrounding your home or the type of plumbing materials used when your home was built. 

Tree Roots

Tree roots are a major headache where plumbing is concerned. The purpose of a tree root is to find water and nutrients for the tree. Your sewer pipes are full of nourishing water, and if there’s even the smallest crack in any of your drainpipes, tree roots will find it, infiltrate the pipe, and cause a blockage or further damage. If a toilet is backing up in your home and you have a lot of trees in your yard, this could very well be the problem. 

Cast Iron Pipes

Was your home built before 1970? If so, it may have cast iron pipes. While strong, cast iron is prone to rust, which can cause vulnerabilities and buildup in your home’s sewer system. 

Terracotta Pipes

Many older homes (those built in the early 1900s) have terracotta pipes because the material was cheap and easy to get at that time. Surprisingly, terracotta pipes are still used in homes today, despite the material being weak and susceptible to cracks and leaks. 

Soil Subsidence

The soil surrounding your home is vulnerable to all kinds of weather changes. Heavy rains, drought, extreme cold, or heat – all these things can cause the soil around your home’s sewer lines to shift, putting pressure on your home’s sewer lines to the point they crack, break, or collapse. 

3 Ways To Fix A Clogged Toilet

Depending on the type of clog you’re dealing with, one of the following fixes will work. Most blockages will clear with the simple method of using a detergent lubricant to wash through your waste pipes, so let’s start with this approach.

1. Soapy Water And Plunger

If your toilet flushes but waste comes back up, the clog could be close to the surface, which can be fixed using hot, soapy water and a plunger. Pour a half-cup of dish soap into the toilet bowl. Let it sit while you boil a large pot of water. Once the water is boiling, carefully pour it into the toilet bowl and use the plunger to work the blockage loose. 

2. Drain Snake

Drain snakes are designed to reach clogs further down in your home’s sewer lines. Most hardware stores carry drain snakes, and there are different snakes for different types of pipes and blockages. For example, if your pipes are smaller than two inches in diameter, a flat tape snake is best. If the blockage is a stubborn one, a power snake, which runs via a motor, might be a better choice than a manual snake. You don’t have to be a plumber to use a drain snake, but if you don’t feel comfortable doing so, don’t hesitate to call in a professional. 

3. Professional Hydro-Jet

Hydro-jetting is a service only offered by a professional plumber. This method of removing blockages in sewer lines requires the plumber to gain access to your home’s sewer system by removing a toilet. He then uses a nozzle to blast up to 4,000 psi of water into the pipes, loosening and clearing away virtually anything that might be clogging your sewer system. 

Solved: Toilet Flushed But Waste Comes Back

Toilet flushes but waste comes back is a common, but frustrating, it is a problem many homeowners face. Luckily, the issue can often be fixed by a confident do-it-yourselfer if it’s a clog near the surface by using hot, soapy water and a plunger. If the blockage is deeper in the sewer system, such as in a drainpipe or the home’s main sewer line, calling in a plumber may be necessary. 

Hopefully, the information above helps you identify the severity of your home’s toilet backup issues, so you can get them fixed right away.

Plumber and HVAC Technician | Website | + posts

As a retired Master Plumber Jamie has over 30 years of hands-on experience, making his plumbing knowledge second to none. He has also worked on both residential and commercial HVAC installation and repair projects.