7 Simple Solutions on How To Fix a Slow Toilet and the Causes

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Is your toilet taking forever to flush? Are you frustrated with the slow draining water and the amount of time and flushes it’s taking for your toilet to evacuate all of the waste? If so, you’re not alone. Learn with us how to fix a slow toilet.

Many homeowners struggle with slow-flushing toilets every day. Apart from it being a major inconvenience, it can be embarrassing when family or friends come over, and can also lead to water waste and increased water bills.

In this blog post, we will discuss 7 simple solutions to fix a slow toilet. We hope that by reading this post, you will be able to repair your own slow toilet without having to call out expensive plumbers and get back to enjoying a quick and easy flush!

What Are The Main Causes of a Slow Toilet?

cropped view of plumber using plunger in toilet bowl during flushing in modern restroom with grey

The toilet is an important part of the house and proper functionality is not only essential but extremely inconvenient when it doesn’t work.

A slow toilet will develop more problems if left unattended. This particular toilet issue can be easily fixed by a relatively inexperienced DIY’er depending on the main cause.

Let’s have a look at the different causes so that we can determine which fix to put in place.

Low Water Level

Typically the toilet tank water level should sit just below the overflow tube. This is generally enough water to create the force required to flush away the waste over the s-curve and then down the drain into the sewer.

The float controls the amount of water that fills the tank. A toilet tank that is not filling up to the point it is supposed to will cause issues when flushed.

Also Read: Easy Steps on How To Adjust the Water Level in Your Toilet Bowl and the Causes

Partly Blocked Drain

When a toilet is blocked it is quite obvious and the blockage can be tackled with a plunger. However, when a toilet is only partly blocked it is harder to spot because it will still flush, be it not too well and you may not notice that there is a block until it’s too late.

Mineral Residue

When the toilet is flushed, the water is forced out of the siphon jets which are situated under the rim of the toilet or the base. If the water in your area is particularly hard and you haven’t ever cleaned the siphon jets then over time the holes will start to develop mineral residue.

This will eventually cause the holes to get congested, not allowing the water to exit with enough force.

Faulty Flush Valve or Faulty Flapper

Photo by ecohome

Another common issue when it comes to a slow toilet can be attributed to a defective flapper or the flush valve mechanism. The flush handle, overflow tube, chain, lever, and flapper are all part of the flush valve mechanism.

When you press the button or pull the handle the lever lifts the flapper up, over the outlet valve allowing the water to flow down the tube. If there is an issue with any part of the flush valve mechanism or a crack in the flapper then the flush will be compromised.

Clogged Air Vent

Air vents are an essential part of the plumbing system in a home. The vents sit on the rooftop and typically have two jobs.

One is to prevent the gasses from building up within the drain pipes and releasing into the home and the other is to permit the wastewater to flow in the drain pipes without pressure building up by allowing air in the pipes.

Blocked Siphon Jets

Siphon jets are responsible for shooting water out into the toilet bowl and flushing the waste away down the drain. Over time these jets get obstructed by mineral residue if they are not cleaned resulting in reduced water and a weakened flush.

How To Fix A Slow Toilet

Plumber repairing toilet tank in bathroom plumbing at home changes the repairing toilet tank

Pinpointing the cause of your slow toilet can take the guesswork out of knowing what the problem is. Most of the solutions we mention below can be attempted by any individual with a nominal DIY experience.

Fix Low Water Level

Low water level issue is possibly the most simple problem to fix when it comes to slow toilets. Adjusting where the float sits on the water surface will either reduce the amount of water in the tank by lowering it or, increase the water by raising the level of the float.

Unblocking a Partly Blocked Drain

This is a common cause of a slow toilet and has a relatively easy fix. Simply grab a plunger and push down a few times dislodging any blockages.

If you have large items stuck in the toilet bowl such as feminine products or a child’s toy then a drain snake or an auger may be better suited to tackle this kind of block.

Removing Mineral Residue

Hard water will cause calcium build-up which will eventually start to block the toilet and slow the toilet drainage. Empty the toilet bowl and pour distilled white vinegar and throw in a cup of baking soda.

The mixture will start to fizz, leave it to sit for an hour. Get a hard brush and remove the mineral build-up by scrubbing it away.

Replacing a Faulty Flush Valve or Faulty Flapper

The flush valve mechanism as you now know has many moving parts so you will need to remove the tank lid and check if anything is stuck or broken. If you are unable to resolve the problem then you may need to replace the entire flush valve mechanism.

The flapper on the other hand can crack or warp over time so replacing that will fix the issue immediately.

Cleaning the Air Vent

Hands in protective gloves clean air ventilation grill, HVAC

If the toilet vent is jammed by leaves or something else it will cause the toilet to drain slowly. You will need to climb to the rooftop and clear out the valve opening, removing anything that may be obstructing the flow of air.

Be extra careful when working on the rooftop as it can be quite dangerous so take the necessary precautions.

Clean the Siphon Jets

Siphon jets are simple to clean if you know what you are doing. Use vinegar, baking soda, and some duct tape to clean out the jets. Empty the toilet tank of water and turn your water supply off. Stick the duct tape over the holes and pour white vinegar and baking soda down the tube and leave it to sit for an hour.

Remove the tape and use a brush to remove any stubborn residue from the holes. Turn the water on and flush the toilet a few times. You can find a detailed article on how to clean siphon jets on our site.

Hot water and Dishwashing Soap

Pouring boiling water first down the toilet can cause the bowl to crack so we would recommend pouring warm water to heat up the ceramic first and then pouring boiling water into the toilet bowl.

This will help dislodge any debris or waste. Follow this by pouring dishwashing soap down the toilet bowl. Leave it to sit for about 20 minutes and then flush the toilet.

Baking Soda and Hot Water

Most people have baking soda at home and it can be used to help in a slow toilet. Simply pour a cup of baking soda into the toilet bowl and pour boiling hot water on top.

Let the solution sit for a couple of hours before flushing the toilet.

Drain Cleaner

These cleaners are not very environmentally friendly so we will leave it to you to decide.

Pour half a bottle of the drain cleaner into your toilet bowl and let it sit for around 20-30 minutes. Ensure the drain cleaner is ceramic-friendly and follow the instructions on the bottle for safety.

How to Prevent a Slow Toilet

woman cleaning bathroom toilet
Unrecognizable woman cleaning bathroom toilet

A slow toilet can be extremely inconvenient and embarrassing when friends or family visit. A well-maintained toilet will not only function better but you can avoid issues like a slow toilet.

Clean the Toilet

Cleaning the toilet by pouring baking soda once a month with some boiling hot water will reduce the chance of the drain getting blocked.

Avoid using harsh chemicals as these are not only bad for the environment but give off toxic fumes that can be dangerous to you, your kids, and your pets.

Boiling Water and Dishwashing Liquid

This is a great preventative measure for blocked drains and is very simple to do. Boil a kettle of water and simply pour it down the drain followed by some dishwashing liquid. Leave for 20 minutes and then flush your toilet. If you do this once a month your toilet won’t get a chance to get blocked.

Toilet Paper Too Thick

Some toilets have small P-traps that get easily clogged by thick toilet paper having you reach for that plunger over and over again.

There are a few solutions here, firstly you can try to use less toilet paper or simply not flush the toilet paper in the toilet and put it in a plastic bag and dispose of it.

Alternatively, you could buy thinner toilet paper which flushes easily. Finally, you could install a wash gun that will allow you to wash your behind which is not only more hygienic but will reduce your toilet paper costs.

FAQS Frequently Asked Questions

How does a toilet work?

A toilet uses gravity and force to eliminate waste down the drain. The force comes into effect when you pull the lever to flush the toilet releasing the water from the tank into the toilet bowl via the siphon jets.

Once the water flows over the p-trap, it creates a pressure system where it will drag whatever is in the toilet bowl with it until the water finishes.

What can you pour down a toilet to unclog it?

Typically, you want to pour baking soda first followed by distilled white vinegar. The mixture will fizz up for a minute or two and then subside, leaving the mixture for an hour.

Use a toilet brush to scrub as far as you can go in the toilet bowl and flush the toilet a few times.

Will a slow-draining toilet fix itself?

It really depends on what is causing the clog. If it’s human waste and toilet paper then it will most likely dissolve in time.

However, if the blockage is caused by non-degradable items such as tampons or even a child’s toy then it will need to be removed before a normal function is restored.

What causes toilets to run slow?

Generally speaking the main causes for a slow toilet is not enough water in the toilet tank, a blocked toilet drain, a blocked toilet air vent or a mineral build-up in the siphon jets or the toilet drain pipes.

Why is my toilet flush not powerful?

If your toilet doesn’t have a powerful flush then you can increase the amount of water that flushes into the bowl by adjusting the float to allow the tank to fill up further.

Alternatively, check the condition of the flapper and whether the siphon jets are obstructed.


A slow toilet can be very annoying and even though there could be a number of issues causing the problem the fixes are relatively simple and do not require a plumber call out. We hope this article has been helpful in identifying the main cause of your slow toilet and how to fix it.

Remember to do regular checks on your toilet and you can avoid the frustration and expensive callouts.

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