Why is the toilet making bubbles after being flushed?

If your toilet has never bubbled before then this is cause for concern. Let’s check several things starting from least to worst-case scenarios. Remember, the bubbles or gurgling sounds are a symptom of a problem that could be serious.

Check for Faulty Parts

The first thing to do is check inside the tank for faulty parts. Check the flapper or disc seal ring for wear and tear. A bad part here would let water leak out of the tank and maybe it was only partly full when you flushed, so it didn’t flush all the way and that could cause some bubbling. This is an easy fix if you’re handy. Just replace the flapper or seal and you’re back in business.

Check the Fill Valve

Another thing to check is the fill valve. Sometimes they get clogged with tiny bits of debris from the water supply and won’t let the tank fill properly. Again, you’ll get a poor flush which could cause some bubbling in the toilet bowl.

Check the Venting System

The third thing to check is the venting system for that bathroom. Without good airflow in your drain system, a toilet will definitely bubble or make gurgling noises. In newer homes or remodeled or added on bathrooms you’ll often find the system is vented by an air admittance valve. If one of these devices goes bad it will definitely cause a  bubbling or gurgling toilet. Replace the air admittance valve and things should go back to normal.

Consider a Toilet Defect if it Is Cheap

One more thing. If every other plumbing fixture in your home is working and draining properly and it’s only one toilet that’s bubbling or gurgling, you could just have a cheap toilet or it has a defect from manufacturing. Although rare, we have run into this problem a time or two.

So the above scenarios are easily fixed malfunctions that can cause toilet bubbling.

Worst Case Scenario – Main Drain Line or Branch Line Clog

Let’s move on to the worst-case scenario. You have a main drain line or branch line clog and it’s manifesting itself with bubbling and gurgling toilets. A mainline clog will be affecting everything in your house. A branch line clog may only affect one bathroom. Most of the time, in our experience,  if it’s only a branch line that only has part of your plumbing drains clogged, it’s because of “flushable wipes.” Flushable wipes are a major plumbing expense waiting to happen. If you must use them, only dispose of them in a trash can. Do not flush them. 

The next question to ask yourself if you do have a mainline or branch line clog, is where is the clog? If your home has exterior clean-out access, go and remove the screw-on cap. If you see standing water in the pipe, then the clog is between your house and the sewer tap near the street. Most of the time the cause of your clog is roots growing into the pipes somewhere between the house and the street. You’ll need a big cable sewer machine or better to clear this type of clog and you should call a plumber to clear it.

If your remove the outside clean-out access cap and you don’t see standing water, then the clog is somewhere in your house. If this is the case, your need to remove the toilet that’s bubbling or gurgling that’s nearest to the outside clean-out access. You should have a wet/vac handy to suck all the water out of the toilet first. This is your access to the pipes that are clogged.

Again, you’ll need a heavy-duty sewer cleaning machine. We use a Rigid-Flex Shaft machine for inside work because it’s a lot neater and cleaner to use inside a home and doesn’t make a mess.

So let’s recap the possible reasons a toilet may be making bubbling noises:

  • Faulty flapper or disc seal
  • Faulty fill valve
  • Faulty venting
  • Faulty toilet: cheap or manufacturing flaw
  • Branch drain line clog
  • Main drain line clog

The time to act is as soon as you notice bubbling or gurgling noises in one or more toilets. If you wait and hope it goes away, you could end up with sewage flooding your home and no one wants that, you or me. The sooner you address the problem the better for your home and your wallet.

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