Why Your Toilet Flushes Slow-And How To Fix It?

Often, homeowners will be uncomfortable with struggling with a slow flushing toilet. Although the problem is not uncommon, various causes result in the same effect. Therefore, for a toilet to function correctly, it needs enough water and no blockage in the drainpipes. So, what are some possible causes of a slow flushing toilet?

Most commonly, a slow flushing toilet results from a blockage in the drain. Other possible causes include low water levels and a damaged fill or flapper valve. Some blockages can be serious, like items that do not disintegrate, whereas others are manageable, like debris build-up.

Consequently, if the problem does lie with the toilet itself, a solution will be easy to come by; however, a drain or venting problem will require a professional. Without further or do, let’s look at the various causes hindering the toilets flushing and how to solve the respective issues.

What Is The Most Common Cause Of A Slow Flushing Toilet?

The most common cause of a slow flushing toilet is a blockage somewhere in the drain or the “s” trap. Due to its inconvenient shape, most homeowners encounter problems in the “s” trap, the pipe below the bowl shaped like an S. Waste, debris, and objects that are not supposed to be disposed of in the toilet quickly get stuck in the trap hinder flushing.

As a result, using too much toilet paper can slow down the flushing process as the material doesn’t break down immediately. In addition, if the water flow is not strong enough or the quantity of water is not satisfactory, disposing of waste when flushing will also prove difficult (I will delve into more detail on this later).

a man with plunger trying to unclog the toilet

Possible Solutions For A Clogged Drain

The following are some basic steps a homeowner can take to clear a clog in the drain:

  • Firstly, probably the most reliable and efficient tool is the plunger. Creating a strong force of air and water to flow through the drain is often the best solution to clear any solid debris inconveniently stuck.
  • Secondly, before using any strong chemicals, you can use baking soda and white vinegar to clear general debris build-up, as the combination of the two is a natural solvent. After a three-hour waiting period, once the baking soda and vinegar were applied, the toilet should run naturally unless the clogging is more severe and solid.
  • Thirdly, similar to the natural solvent combination, another simple solution is combining hot water with dishwashing soap. As previously stated, a general build-up of debris can be cleared with a few natural remedies, granted that the build-up is not too severe and solid. The combination will also loosen the debris, making it easier to plunge away.
  • Finally, once natural solvents are used to clear the drains and loosen the debris, you can use any thin scraping tool to clean the jet holes found below the rim of the toilet. The jet holes accumulate debris fairly quickly and require a physical clean-up as wastewater flows through them daily.

What Are Some Other Causes Of A Slow Flushing Toilet?

As promised, an efficient water flow problem will also affect the effectiveness of the flushing. The toilet needs enough water for a flat flush to function properly. The quantity of water creates pressure resulting in an even flow to dispose of waste. Some toilets have a more efficient flush using less water but more power, consequently creating a shorter flush.

Regardless of the differences, homeowners should ensure that the water in the tank is not too low and that the available water creates enough pressure to dispose of waste. Luckily, the issue can be solved by a slight adjustment in the function of the toilet.

The function of the fill valve is to refill the tank with the correct amount of water succeeding a flush. If there is damage to the valve, water will continuously flow even after the flush has finished; however, damage to the fill valve is not the only problem. An inappropriate adjustment also causes weak flushes. In addition, any damage to the flapper or fill valve causes slow flushing.

Similar to the fill valve, the flapper valve will also be ineffective if the adjustments aren’t appropriate for the toilet or if there is damage-causing leakage.

How To Solve The Water Flow Problem Of A Toilet?

The symptom of a water flow problem is a bowl that’s not filling quickly enough with water. First and foremost, you should check that all the adjustments are appropriate for the function of your toilet in the tank. For Example:

  • The chain connecting the lever and the valve should not be too tight to restrict the flapper from resting on the valve, but it should be tight enough to lift the flapper for an ideal amount of time when flushing. Ideally, the flapper should be open for at least 3 seconds to provide enough water for waste removal.
  • As previously mentioned, a water flow problem can also result from an adjustment issue. Depending on the diagnosed issue, one can simply disconnect the chain and create more or less tension by placing the link higher or lower on the chain itself.

If there is still a water flow problem after the toilet has been adjusted, it would be wise to call a plumber as a possible problem might be the flow of water to the tank from the pipes.

How To Solve A Fill Or Flapper Valve Issue

Both the fill and flapper valve can be replaced without a plumber; however, damage to the valves might not be the only cause of problematic flushing, and a professional diagnosis is advised.

Regardless, you can switch the water supply to the toilet and empty the remaining water in the tank by flushing. Once the tank is empty, a new fill valve can be added by unscrewing the nut connecting the current valve and the hose. Similarly, the flapper can also be replaced following the steps mentioned above.

Buying new valves come with instructions to correctly place them in the tank, and homeowners will be able to succeed without professional assistance.

When Should I Call A Plumber For A Slow-Flushing Toilet?

It is advised to seek professional help if you are not sure of the cause of the problem yourself. Although some of the issues are not that serious and can be solved with natural solvents and a bit of elbow grease, plumbers are trained to seek lasting solutions that are beneficial for the longevity of the toilet.

On the other hand, one should call a problem when the blockage is in the sewage line and not in the toilet. Due to sewage lines being under the floor, it is susceptible to more than just debris build-up and will require a professional to diagnose the problem and its location in the pipes.


Blockage in the toilet is the most common cause of a slow flushing toilet. Generally speaking, homeowners can fix the problem themselves by flushing natural solvents down the drain, using soap and hot water, and even plunging away to create a bit of intentional air to force out the gunk. However, be sure to diagnose the problem before making unnecessary adjustments.

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