Why Toilet Bowl Water Level Recedes – The Main Reasons

What are the main reasons why toilet bowl water level recedes? Depending on which toilet brand, the water surface in the toilet bowl is approximately five to seven inches below the toilet seat. It could be that your water level is dropping if it’s not there.

Two reasons bowl water may recede or drain completely is: either the blocked vent pipe causing a siphoning effect on the water in the bowl, or a crack in the toilet bowl causing water leaking to the floor.

There are simple and quick fixes for both of these problems. Continue reading to learn more about these issues. There are some great tips that can help you prevent water loss in your toilet bowl.

Possible Reasons

Why Toilet Bowl Water Level Recedes

Two reasons water levels may be falling are: You could have a crack in the toilet bowl that allows water to leak onto your floor or down your drainpipe. It would be simple to see if the water is on the floor or down the drainpipe.

A blocked drain vent could also be the cause. Your drains all connect to the sewer. However, they also link to the vent that leads to the roof of your home. As water flows down the drain it forms a seal, causing low pressure and gravity to pull it down. This is why toilets flush.

The vent system pulls air into the drains’ low-pressure areas. This stops air from being drawn through drains unnecessarily, and potentially harmfully.

If a vent is blocked, it means that water will still need to draw air when it drains from a tub or sink. This air can be drawn into the toilet through the drain, possibly drawing water.

How to Find the Cause

How to Find the Cause

It can be difficult to spot a hairline crack in your toilet bowl. To see the vent, however, you will need to climb up onto the roof.

How do you determine the problem? There are two simple steps that you can take to determine the problem.

  • Run your faucets. First, make sure that your toilet is fully emptied. Next, run the tub faucet and sink.
  • You should listen for gurgling. You should hear the air passing through your toilet drains gurgling.
  • Decide what you heard. If the noise is gurgling, it’s most likely that the vent is at fault. Continue if you don’t hear any gurgling.
  • All faucets must be turned off. The test will require you to stop using water until the end.
  1. Fill up your toilet. Make sure your toilet is full and mark the location.
  2. Take a moment to wait. Give it an hour.
  3. Check the water level. If the water level drops without any other drains, it could be a leak through a small crack.

Toilet tanks often have a mark that indicates the water level. If the mark on your toilet is not correct, make sure that the water level is approximately 12 below the overflow tube.

Why Does the Bowl Water Level Recedeы/Drops?

Bowl Water Level Recede/Drops

As a result of the water pressure in the bowl, the water level could drop. A pressure difference will occur if water is entering the bowl at a faster rate than it will naturally flow through the trapway/hump.

The water level will rise as the water levels are higher. This causes the bowl water to flow faster and the water to drain into the drain more quickly than usual. This is how the bowl water recedes and can empty the drain completely.

However, this is temporary. The two most common causes of water dropping or draining are a crack in your toilet bowl or a blocked drain vent.

Don’t forget about sewer gases. All drains are connected with the sewer and to the air vent at the top of your house. Any air drawn from the drainpipe will release low pressure and cause any air seals to be broken.

The clogged drain vent can block airflow and cause it to draw air from the vent pipes. It can also siphon water from the sinks, toilet bowls, and tubs. The clogged vent is one more reason is why water continues to recede.

It is not uncommon to see cracks in the bowl, particularly at the base. You can only spot it by looking for water in the area or at the toilet’s surface.

Cracked Toilet Bowl

Cracked Toilet Bowl

Another reason for low water levels in the bowl is the damaged toilet bowl.

Follow these steps to find out if your toilet bowl cracked.

First, fill the toilet with water. Turn on the faucets. Turn the faucets off after filling the toilet.

Second, measure the water level of the toilet bowl. Give it a while.

Check the water level. If the level drops, it is likely that water is leaking from the crack.


As a solution, however, you will need to replace the toilet bowl. Here’s how to do it yourself.

Step 1

First, shut off the water supply to your toilet. Next, turn off the water supply to your toilet.

After draining the tank and bowl, you can use a sponge for complete removal.

Step 2

Unscrew the bolts and nuts to remove the toilet from the flooring. Use the wrench to unscrew the bolts and nuts.

The unscrew water hose that brings water to the tank and then takes out the mounting nuts that attach the tank to your toilet bowl.

After you have removed the toilet, it is time to take the toilet off the floor. If the toilet is too heavy to lift, remove the tank first and then the bowl.

Step 3

You are now ready to install the new toilet bowl.

To put the toilet bowl together properly, do the opposite of the screwing.

Other Causes

Pets, such as dogs and cats, maybe drink from the bathroom bowl. This could cause a drop in the water level. To prevent this from happening, you will need to lower the lid. The toilet might contain chemicals.

Tampons and other debris are other options. They can become stuck in your toilet’s bend, slowly reducing the flow of water down the waste pipe. You can use a toilet auger for this purpose.

Diagnose a leaky toilet

Diagnose a leaky toilet

A toilet could leak in many places, causing water to seep from the bowl. It is often possible to fix the problem by following a few easy steps. These problems can be solved with just a few tools in most cases.

Step 1: Inside the Tank – The Flapper Valve

Take off the lid of your toilet tank. The flapper valve is located at the bottom of your tank. The flapper valve is connected to the flush handle via a short-length chain. Other types of flapper valves can be connected directly. The concept is the exact same.

Step 2: Open Flapper Valve, and Inspect The Flapper

Sometimes, water leaking from the flapper valve can cause the toilet bowl’s level to drop slightly. The tank’s valve ring must be sealed tightly by the flapper valve. The flapper valve may fail to seal properly if it is damaged.

Examine the flapper valve’s outer edge for cracks, wear, tears or tears. Some flapper valves can become so soft from age and usage that they don’t seal. Replace the flapper if you suspect the flapper is leaking. Flapper valves can be purchased at most hardware and home improvement stores.

Step 3: Tank Water Level Issues Adjust your float

The tank flush valve might not work properly if the water level is too high or low. If the flush valve isn’t working properly, the toilet bowl can recede and not flush correctly.

The recommended water level is indicated on most toilet tanks. To bring the water level up to the mark, you can adjust the float valve located in the water tank. You can adjust the float valve by turning a screw or by bending the arm of an older system.

Step 4: Seals & Gaskets

There are many seals and gaskets on your toilet. A gasket is placed between the tank of a two-piece toilet. This gasket can dry out, shrink, crack, or become damaged over time. Leakage can occur if the seal is damaged. This type of leak is easy to detect. Leakage at the seal could cause the tank flush system not to deliver enough water for a proper flush.

A seal ring is located at the base of the toilet, where it joins the waste the plumbing vent pipe. This seal ring could be wax or a man-made product. If the bolts that hold the toilet to the ground are loose, this seal (or bowl ring) can be broken. The bowl ring will lose its seal if the toilet moves even slightly.

Many homeowners feel confident about tackling the task of replacing a bowl ring or tank gasket. These are jobs that should only be done by licensed plumbers. These types of repairs are required by some local building codes.

Step 5: Broken or Cracked Toilet Bowl

Water can escape from the bowl if there is a crack in the toilet bowl or any other damage. A leaky toilet bowl will cause a drop in the water level. If objects fall into the bowl, or the toilet is under undue stress, damage to the toilet bowl may occur.

Sometimes cracks or damage are easily visible. Cracks and holes can be left by objects falling into the toilet bowl. Hairline cracks can be difficult to see.

Your toilet should not be used as a step stool. The toilet is not a step stool and can crack or collapse if it is subject to excessive stress. Uneven pressure can cause cracks in the toilet’s corners or at the base. Any toilet with cracks or damage must be replaced immediately.


We discussed in this guide the reasons why the water level of the toilet bowl keeps dropping.

Follow the above-mentioned remedies to get rid of this problem. If none of these solutions work, you should call a professional.

Most likely, your plumbing system will be in serious trouble. If your toilet is absolutely broken, you can check our toilet reviews.

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