Drains
June 20, 2025

Fast Plumbing Answers: Bathtub and Toilet Clogged?

Bathtub and toilet clogged? It's probably a blockage in your branch drain line. We're Mother — we'll help you diagnose your plumbing problem in 2 minutes.
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Patrick Shea
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Mother
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Editor's Note

You’re here because your bathtub and toilet are clogged in the same bathroom, at the same time. So what’s going on — is it one clog or two? How did this happen, and how can you fix it quickly? 

Let’s answer all your questions in 2 minutes or less.

We’re Mother, a Dallas-Fort Worth plumbing company that provides dependable, hassle-free modern plumbing for homeowners who value quality. If you ever need us, we’re here to provide you long-term plumbing solutions that last.

How Your Bathtub and Toilet Clogged: The Fast Answer

There are 3 primary reasons for a simultaneous toilet and bathtub clog, but you’re most likely dealing with a blocking in the branch drain line — the dedicated drain pipe that serves the toilet and bathtub.

Most times, these branch drain line blockages happen when too much hair, soap scum and paper products go down your bathroom drains.

Bad news: you have a clogged drain pipe. Good news: it’s almost certainly one clog in one pipe, not two separate clogs. It’s still a pain, but it’s a way easier fix.

2 other less likely causes for a toilet and bathtub clog

There are 2 other less likely causes for your toilet and bathtub to be clogged at the same time:

  1. Partial main line blockage. This clog or blockage would be further down the main line from your branch drain line. You’d notice slow drainage effects in the bathtub before the toilet.
  2. Obstructed plumbing vent. If leaves or debris are blocking the air vent that serves your bathtub and toilet’s drain pipe, this can form a vacuum that slows or stops drainage.

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4 Warning Signs of a Toilet Branch Drain Line Clog

We’ll start this section with a brief heads-up — some of these red flags are pretty gross, and we hope you haven’t noticed any of them.

If you’ve noticed any of these plumbing issues in your bathroom, you may have a branch drain line clog:

1. Toilet backing up into bathtub: Gross, but there’s a simple explanation. Your bathtub drain is lower to the ground than your toilet drain. 

If there’s a clog in the shared branch drain line, wastewater from the toilet backs up into the lowest drain possible — that’s your bathtub. 

2. Uneven toilet bowl refilling: Specifically, check if the water level in your toilet bowl rises and falls without flushing.

3. Gurgling sounds: If your bathtub drain gurgles when you flush the toilet, or your toilet drain gurgles while you take a shower, that’s an indicator of a branch line clog.

4. Slow drains: While slow or inefficient drainage from your toilet and bathtub is an easy indication of a drain clog, it could also indicate a number of other plumbing issues. Look for any of the other symptoms on this list in tandem with slow drainage.

More Fast Plumbing Answers About Drain Clogs

Toilet keeps overflowing after your flush?

Drain not working (even after plunging and Drano)?

Bathroom smells like sewage?

Toilet always clogging?

You Found the Issue. Here’s What to Do Next

Slow bathroom drains make everyone nervous, and nobody wants toilet water in their bathtub. But now that you know what’s going on, let’s talk about how to fix it.

A branch drain line clog isn’t a DIY fix. You’ll need to call a local plumber — ideally, one with experience clearing blocked main lines and drain pipes. 

There’s very good news: You caught the clog before it became a persistent issue, and likely saved yourself a ton of money (and headaches). If left unchecked, these branch drain blockages can easily cause burst drain pipes and sewer line damage.

If you live in the DFW Metroplex, give Mother a call. We offer $299 drain cleaning service with a complimentary video camera inspection and free bottle of Endure, which we rated the best drain cleaner for organic clogs.

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Fast Plumbing Answers: Bathtub and Toilet Clogged?