Toilet Flushes Slow But Is Not Clogged? (Possible Causes & Fixes)

Matthew Mountain
by Matthew Mountain

No fixture is more synonymous with the modern bathroom than the toilet. When this essential fixture is working properly, it provides a much-needed function. When a toilet malfunctions, however, the problem is either major or minor.

A specific malfunction is when a toilet flushes slowly. There’s a difference between a slow flush and a clog, and this article focuses on the slow flush. If you want to know what causes a slow flush, solutions for this problem, and other important toilet-related information, then this article is for you.

If your toilet is flushing slowly, then there could be a problem with the pipe that’s connected to your toilet. Also, the flapper valve could be preventing a seal from forming, or there could be a problem with your toilet’s wax ring. Lastly, there may be a block in the sewer line, one that the local water company will have to clear.

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How a Toilet Is Supposed to Flush Normally

Before addressing a malfunctioning toilet, I must first break down how a toilet is supposed to work normally. A lot of toilet users don’t understand how this bathroom necessity works, as they’re used to doing their business, flushing, and not worrying about what happens next.

If you know how a toilet is supposed to function, then you’ll have a much easier time identifying what’s wrong when a problem occurs. Listed below are the main components that all toilets include:

  • Handle
  • Fill Valve
  • Tank
  • Overflow Tube
  • Flush Valve
  • Flapper Valve
  • Siphon Jet

Toilet Flushing Broken Down

Step One: The fill valve fills the tank with water after the toilet is flushed. Once the tank has been refilled, the fill valve will deactivate. Whenever water flows from the tank—including when the flapper is leaking—the fill valve will turn on to ensure that the tank has an adequate water supply.

Step Two: The toilet flapper valve, which sits on the flush valve, is connected to the flush lever by a chain. When the toilet is flushed, the flapper lifts off the flush valve, allowing the tank water to exit and flow without obstruction.

Step Three: When the toilet is flushed, water will go from the tank to the bowl via the flush valve.

How Important Is a Proper Seal?

One will also need a tank-to-bowl gasket to ensure there’s a leak-free seal, as toilet tank/bowl leaks can be costly and a pain to deal with.

But keep in mind that a wax-free seal kit could be used instead of a traditional wax ring. The wax-free gasket creates a tight seal—just like a traditional wax ring would—but the wax-free solution lasts longer and provides a tighter seal. There needs to be some kind of seal between your toilet and the bathroom floor, as without this you’ll have to deal with water and sewer gas leaks.

Identifying What’s Causing the Problem

When you notice that your toilet isn’t flushing as fast, and the problem isn’t going away on its own, don’t start tinkering with the toilet unless you know what you’re doing. Instead, you should have a deliberate plan of action, one that will most likely end with you getting in touch with a professional plumber.

Even if you can properly diagnose what’s wrong with your toilet, it’s quite likely you won’t have the tools, experience, and know-how necessary to fix the problem on your own. While a lot of toilet-related problems are minor, there are some major ones that only a professional plumber can deal with. If you try to fix these major problems DIY, it’s quite likely this will only lead to more expensive damage and headaches.

If you believe that your toilet is flushing slower than usual, use the process below to pinpoint what exactly is causing the problem.

Step One: Consider the Pipes Before You Blame the Toilet

Before you dismantle your toilet and start fiddling with its inner components, you should first consider the pipes that are connected to your toilet. A slow flush could be linked to a pipe-related problem, and if this is actually the case then there’s probably nothing wrong with your toilet.

If you suspect a pipe-related issue, the first thing you should do is grab the plunger that’s near your toilet. Start plunging until you reach the desired result. Using proper plunging technique is important here, as you’ll need to push down as much water as you can into the pipe so whatever is blocking the pipe is thoroughly removed.

If plunging is all that’s needed to resolve the pipe problem, then your toilet should start flushing normally again. But if you’re still noticing a slow flush, even after a lot of good plunging, then the problem could be one of the common ones below, all of which are briefly explained.

Step Two: Inspect the Toilet Inside and Out

If you suspect that the toilet is causing the problem, the first thing you should do is remove the tank lid so you can look inside. Make sure that the flapper valve is attached correctly to the flush valve, and ensure that the small chain is not hung up on anything.

If it’s necessary, take out the chain and then reinsert it into a different hole on the handle flush bar. If the chain is too loose, it can get hung up on the flapper valve, which would lead to no seal being created and the toilet constantly filling with water.

To ensure that the chain and flapper valve work after an adjustment, flush the toilet. If the water exits the tank correctly, then the problem has been solved.

If, however, the water is still draining slowly, then it’s at this point that you should get in touch with a professional plumber, as there’s probably something wrong with the sewer pipe—or the air pipe if your toilet utilizes this component.

Step Three: Check the Condition of the Wax Ring

If your toilet utilizes a wax ring, and most toilets do, then the slow flush problem could be related to this component. As was already mentioned, the wax ring is used to create a seal between the toilet and the floor. The seal is there for a few reasons, but the most important is that this component ensures the toilet can suction properly.

If your wax ring is not sealing correctly, a slow flush isn’t the only consequence that will be observed. You’ll also notice a bad smell coming from the toilet, and this smell will be emanating from the sewer line that’s under your toilet. Now do you see just how important that little piece of wax is?

If you suspect that the wax ring is the issue, you can replace it yourself. Or, of course, you could get a professional plumber to do this. This latter option is definitely the better of the two, as a compromised seal is something that should be handled quickly and properly.

Step Four: Addressing a Main Line Block With Your Local Water Company

If replacing the wax ring doesn’t fix the slow flush problem, then it’s quite likely the sewer pipe is clogged. If the clog exists between the main sewer line and your house, then you’re the one who’s going to have to take care of this. If, however, the clog exists beyond the “clean-out opening” that’s located near the main line, then the local water company or your municipality is supposed to take care of the problem.

If you’re still having a slow-flush problem—and you’re certain that neither your wax ring or your pipes are the cause—then you should call the water company and see what they have to say. Tell them about your problem and ask them to send someone to your property so the situation can be assessed by a professional.

If you don’t know where the clog is coming from, get a plumber to locate the source of the clog before you get in touch with the water company. A plumber may be able to fix the problem on their own or they may be able to help you explain your problem to the water company.

Do You Need to Install or Repair a Toilet?

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Related Questions

Can an air pipe malfunction cause a toilet to not flush properly?

Yes, an air pipe can malfunction and cause the toilet to not flush properly. Air pipes are not that common, but if you have one of these, then it’s best to get a professional plumber to examine and fix this component for you.

What to do when there’s drain buildup?

If there’s drain buildup, then your toilet could be slowing down. Pour a gallon of water into the bowl and see if the water level rises quickly. If it does, then you’ll know you have a clog somewhere in the pipe. To resolve this problem, use a plunger; then use a snake if the plunger doesn’t work.

What are the jet holes and why are they important?

The jet holes are under the toilet’s rim and these shoot water out during the flush. Since they are out of sight, it’s easy to forget about them. But mineral buildup often occurs around these, and this buildup can block water flow and cause your toilet to slow down. Therefore, you should take measures to prevent mineral buildup, with the most effective measure being routine cleaning.

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Matthew Mountain
Matthew Mountain

Matt loves everything DIY. He has been learning and practicing different trades since he was a kid, and he's often the first one called when a friend or family member needs a helping hand at home. Matt loves to work with wood and stone, and landscaping is by far his most favorite pastime.

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