Why Is Water Coming Up through My Bathtub Drain? (Repair Options & Costs)

If you’ve ever had to deal with murky sewage water coming up out of your bathtub drain, you know how unpleasant that can be.

If you have water coming up through your bathtub drain, it’s most likely because you have a clog in the drain. But don’t panic! You can try using a drain snake to clear debris out of the pipe or a plunger to remove any obstructions before calling a professional for help. 

Let’s take a look at some of the different things that can cause water to back up in your bathtub drain and how you can stop it from happening again.

Why Water Is Coming Up Through Your Bathtub Drain

Although water coming up through your bathroom drain may be distressing, it’s not uncommon.

In fact, many homeowners have experienced this issue before. If it’s happening to you, you should first check if you have a clog in your drain, and second check for signs of a problem with your main sewer line.

You’ve got a clogged drain

The clog could be coming from anywhere in your house like your toilet, bathroom sink, dishwasher, or even washing machine.

You see, the plumbing lines are all connected down below and eventually lead out to the main sewage line so if there is a clog anywhere up the line, water can back up into the bathroom sink, or, you guessed it – your bathtub. 

Clogged drain

It may be obvious that there is a clog if there is standing water sitting in your bathtub that won’t drain down, but there are other not-so-obvious signs too. Like if the toilet is having a hard time flushing or starts making a bubbling noise. Or the sink, bathtub, or shower water is draining very slowly. Also if you smell any bad odors coming out of any of the drains. 

These can all be signs that are pointing toward a clogged drain and you should fix it before the problem gets worse.

You’ve got a problem with your main sewer line

If you didn’t find a clog in any of the drains inside, the problem may be a bit farther down the line in your main sewer line. 

Your main sewer line is the pipe that connects to all of the other pipes in your home and carries sewage out and away from your house. It is buried underground, so it’s hard to see unless you dig around it.

4 Signs that your main sewer line is clogged.
Image Credit: www.wg.scene7.com

So if multiple drains are backing up in your house, the problem is likely in your main sewage line.

Sewer line problems can include clogs, leaks, or even a collapsed pipe. The blockage usually happens when tree roots and other debris enter into the pipe because of heavy rain or flooding, and breakage could happen due to construction projects, or even animals digging around in the ground.

A problem with the main sewer line is likely going to have to be handled by a professional. A plumber will be able to determine what caused the sewer line blockage and he will know how to clear it out. They will also be able to identify whether there is a leak in the pipe or if it’s just a normal clog.

What Causes Clogged Drains?

A clogged drain is the number one cause of water backup in a bathtub. So when this happens, you need to find out where the clog is and unblock it. Then take some precautions to try and prevent sewage backups from happening in the future. 

When it comes to prevention, keeping your home and pipes clean is key. Let’s take a look at a few of the most common culprits of clogged drains.

Tree roots

Tree roots are the most common cause of sewer backups, according to the American Society of Plumbing Engineers

They grow down underground and find their way into your plumbing pipes and sewer line. When they find cracks in the pipes, they start growing inside the pipes. This root growth can lead to leaks, breaks, and even complete blockages.

If you have a lot of trees around your house or on your street where the sewage line would be buried, it’s not a bad idea to take some precautions to prevent damage caused by tree roots. 

Tree roots

Some homeowners install wooden or metal barriers around the pipes to stop the roots from getting in. Others hire a professional to clean the roots out yearly. Flushing rock salt down your toilet is also a popular method that works by sucking the moisture out of the root and killing it. 

Accidentally flushed foreign objects

Flushed toys and feminine hygiene items are the second most common reasons for sewage backups.

Toilet paper is made to dissolve when it gets wet so when it is flushed down the toilet and into the drain, it will not cause buildup to clog the drain. Spoiler alert – other objects like toys, feminine hygiene products, and baby wipes do not dissolve.

So when you flush anything besides toilet paper down the toilet, it will get stuck in the drain and cause everything coming behind it to get stuck. When there is no more room for waste to flow down the pipe, the waste and water will come back up into your home.

Grease and scum buildup

Ever heard of a Fatberg? They’re basically giant balls of fat, grime, and other disgusting stuff that collect in our sewers. And while they don’t pose much threat to human health, they do make life miserable for homeowners trying to keep their pipes clean. 

The problem stems from how grease builds up over time inside sewer pipes. Grease doesn’t just sit around; it forms into little globules that slowly start to accumulate. Eventually, these globules become big enough to block the pipes entirely. When that happens, water no longer flows freely through the pipes. Instead, it gets trapped inside the pipes, causing backups and floods.

If you think that sounds gross, wait till you hear about the other things that can cause clogged drains.

Soap doesn’t dissolve away as you might imagine either. Instead, it builds up over time, gets trapped inside the pipes, and eventually causes blockages. This happens because soap forms lather, which is basically a thick layer of soap that builds up around objects in the pipe. Eventually, the soap becomes too hard to flush out.

How to Unclog Your Bathtub Drain 

There are a few things you can do to try and clear out the clog before calling a professional plumber. To get started you will need: 

  • A plunger
  • A snake
  • A screwdriver
  • A knife
  • A bucket 
  • A wire brush

Cleaning out a clog with standing water in the tub

To clear standing water out of your bathtub, you will need to use your plunger. But first, in order to create a vacuum when you plunge, remove the overflow plate in your bathtub and plug up the venting hole with a washcloth or a hand towel. Otherwise, the air will come right back up through the vent and there won’t be any pressure to unclog the drain. Plunge up and down until the water starts draining out of the bathtub.

Remove any visible blockages

If you can see anything that may be blocking your drain when you look down it, clear it out. The most common obstruction when we are talking about bathtubs specifically is hair

Hair is pretty easy to deal with if you know what you’re doing. The first thing you’ll want to do is grab a screwdriver and unscrew the bathtub plug. Then you will have a clear view of the hair (or object) that is blocking the drain and it’s likely wound around the metal cross wires down the drain. 

Grab a wire coat hanger and bend the end of it with some needle nose pliers or grab some other sharp tool like a knife and pull the hair out of the drain. If you have a lot of hair, you may need to cut it with a knife to get it out in chunks. Once you have removed the hair, rinse the area thoroughly with warm water.

Tip: Don’t use any tools that are small enough to fit down the drain if they fall. Dropping something like that down the drain would cause a worse clog than the hair! (Source)

Use boiling water and salt

I mentioned earlier that rock salt is commonly used to treat clogs caused by roots in your sewer line. But did you know salt can also help clear your bathroom pipes? Since it is abrasive, it is very efficient in removing some light debris and getting rid of some of that soap scum buildup that I mentioned earlier. 

And while it may not be the best solution to unblock a major clog, pouring a saltwater mixture down your pipes is a great way to keep them clean to prevent bigger clogs from happening down the road. 

Start by boiling about 8 cups of water and then mix in a quarter cup of salt. Let it cool down to about 200 degrees Fahrenheit before you pour it down your drains because boiling water may damage your pipes if they are made of PVC or crack your sink/bathtub if it is porcelain. 

If you feel like your pipes could use something a little stronger, you can also add vinegar and baking soda to the mixture. 

Use a plunger

Before you call a plumber to come help, use your plunger to dislodge anything that might be causing the problem. If you are plunging your bathtub, make sure to follow the steps I mentioned above to plug up the overflow pipe and create pressure when you plunge.

If there isn’t already water in the bathtub, turn the faucet on and fill up the bathtub with enough hot water to cover the base of the plunger. Begin to plunge up and down until the clog comes loose. 

Clean the p-trap 

The p-trap is the p-shaped pipe that sits directly under your bathtub or any other basin that collects water for that matter like your sink or toilet.

Its purpose is to prevent unpleasant odors from coming back up from the sewer and out of the drain for you to smell them. It works by staying filled with water in the curved “U” portion which acts as a barrier between the sewage odors and the air above in your bathroom. So to keep it working properly, it should be cleaned regularly.

To clean your p-trap:

  1. Turn off your faucet.
  2. Unscrew the p-trap (either with your hands or a wrench) – make sure to have your bucket nearby for this step since there is likely water sitting in the pipe. 
  3. Clean the inside of the pipe with a flexible wire brush.
  4. Put the p-trap back together. 

Use a snake 

I would recommend using a drain snake if a plunger doesn’t fix the problem, or if the clog is rather large. A drain snake is a long, flexible metal cable designed to push objects out of the pipe.

You can send the drain snake down through the bottom drain of your bathtub or down the overflow pipe – whichever is easier to access. First, remove the drain cover, and place the end of the snake in the pipe. Turn the dial on the other end of the drain snake so that the cable rotates down into the drain. Keep feeding the cable down into the pipe until you hit the clog. At that point, you can either try to push the clog through or pull it back out with the snake cable.

You may need to use a little bit of muscle with the snake, but don’t attempt to force it through because jamming the cable too hard into the drain can cause serious damage to the plumbing system.

How Much Does it Cost To Fix Your Bathtub Drain?

If you’re looking to save money on fixing your bathtub drain, you can of course take the DIY route with the solutions that I detailed above. But if you’ve gone through my suggestions and still cannot fix the clog, you will have to call a plumber.

The problem may be too far down the plumbing or sewer lines for you to get out or it may not even be a clog after all. If your main sewer line is busted, for example, due to overgrown roots, you will need a professional to replace it and that could get costly. 

Here is an idea of what the different situations would cost if you go the DIY route, or decide to hire a plumber.

Unclog a drain$5-$10 for a plunger$75-$200
Drain cleaning $5 (salt and water method)$100-$250
Clearing roots out$10 (rock salt or foaming root solution)$200-$300 per year to clear the roots 
Drain Snake$25-$50 (to purchase)$100-$250
Pipe replacementnot recommended$50–$250 per foot of pipe


So,if you are in the unfortunate situation of water coming up through your bathroom drain, know that while it is not normal, it is not uncommon.

There are several possible causes for this issue, including clogs, leaks, and blockages, however, it doesn’t necessarily mean that you need to call a plumber right away.

If you go through the steps I’ve pointed out above, 9 times out of 10 you will be able to clear up the problem on your own. And if all else fails, call a plumber to help you find and fix the problem.

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