Why Is The Water in My Toilet Bowl Low?

If you’re experiencing low water levels in your toilet bowl, you may be wondering what’s causing the issue and how to fix it. While this problem may seem like a minor inconvenience, it can actually indicate underlying plumbing issues that require attention.

In this article, we’ll explore some of the most common reasons for low water levels in toilet bowls, as well as tips on how to diagnose and resolve the problem.

How Much Water Should Be In the Toilet Bowl

The water level in a toilet bowl is directly related to the water level in the toilet tank. Too much or too little water in the tank will affect how much water flows into the bowl. Knowing this, the water level in a toilet tank should fall an inch or two below the fill valve /overflow tube. If you look closely at the inside of your toilet tank, you may even find a mark that tells you where the water level should sit. 

As for the toilet bowl itself, the water level should be high enough to cover the P-trap/drain sufficiently. If the water level is too low, the toilet may not create enough suction to flush completely, or sewer gases may be able to escape up through the drain and into your home. 

Air Trap Water Level. - Why Is The Water in My Toilet Bowl Low
Correct air trap water level

A final note on toilet bowl water levels: Every toilet is different, which means the water level in the bowl will differ from commode to commode. For example, low-flow toilets have a lower water level in the bowl than regular toilets. 

8 Reasons Your Toilet Water Level Is Low

Now that you know where the water levels in your toilet tank and bowl should sit, let’s explore some of the reasons your toilet bowl water isn’t where it should be, so you can get it fixed as soon as possible. 

1. Check the Water Supply

The most common reason for a low water level in a toilet bowl is a lack of water. If something is amiss with the water supply leading into the toilet, it may not fill completely, resulting in the low level you are seeing. 

Check the water supply valve located behind or underneath your toilet tank. The valve should be turned all the way counterclockwise to allow for the highest water flow and pressure. 

If you find that it is turned part or all the way clockwise, there won’t be enough water pressure to adequately fill the tank, thus causing a low water level in the toilet bowl.

Turn the valve as far as you can counterclockwise and wait for the tank to fill. Once it is full, flush the toilet and see if the bowl fills normally. 

2. Check The Fill Valve and Tube

The fill valve controls the flow of water into the toilet tank. You will find is connected to the overflow tube. If the fill valve is worn, damaged, or clogged, it can lead to restricted water flow or no flow at all. 

Fixing is usually as simple as aligning it or reconnecting the fill valve to the overflow tube if they are disconnected. Inspect the fill valve for any visible signs of damage or mineral build. If you flush the toilet and observe how the fill valve operates as the tank refills, you will be able to check for problems. If the tank fills with water to the normal level, the fill valve is working fine.  

Note: The fill valve can be adjusted using a screwdriver to raise or lower the water level in the tank. Turn the screw clockwise to allow more water to fill the tank. Again, flush the toilet to see if the water fills to its correct level. 

3. Is A Clog Causing Siphoning

While most toilet clogs cause the bowl to overflow, some clogs can cause the opposite effect and siphon water out of the bowl until little or no water remains in the toilet bowl’s neck. 

To check for siphoning, flush the toilet and watch the water level in the bowl. If the water level rises and then drains away until there is hardly any water remaining, then, you have a siphoning issue likely caused by a clog somewhere down the waste pipeline. 

To clear the clog, use a flange plunger to dislodge the blockage. If the blockage is stubborn, you may need to use a toilet snake to clear it. Once the clog is cleared, your toilet should flush normally with the water level in the bowl sitting at the correct level.

4. Check Inlet Jet Holes

The inlet holes, often called rim jets, are tiny holes located underneath the rim of the toilet bowl. This is where water from the tank enters the bowl when you flush the toilet. 

If you have hard water in your area, these holes can become plugged with mineral deposits that can partially or totally block the flow of water. Which can prevent your toilet bowl from filling to the appropriate level. 

If you suspect blocked rim jets, take a small mirror and hold it below the level of the rim so that you can look under the toilet rim to check for mineral buildup. 

The easiest way to take care of this issue is to pour hot white vinegar into the overflow tube inside the tank. Allow it to sit for several hours to dissolve any hard water buildup that might be present. 

I would also recommend filling a spray bottle or container. Spray the solution generously around the rim jets and let it sit for at least 30 minutes to help dissolve the mineral buildup.

After allowing the vinegar to do its job, scrub the rim jets with a stiff bristle brush and flush the toilet a few times to completely remove any particles. 

5. Toilet Bowl Crack

Have you noticed any water on the floor near your toilet? If so, it is possible that you could have a crack in your toilet bowl, a leak from the wax gasket seal, or associated pipes. 

Inspect the outside of the toilet bowl carefully. Even the smallest hairline crack can allow water to leak from the bowl, so take your time as some cracks can be difficult to see. If this is the reason for the low water level in your toilet bowl, the only resolution is to replace the entire toilet. 

This can be a challenging task, so be sure you have help, or, if you aren’t comfortable doing it yourself, call a plumber to replace the toilet. 

6. Clear Sewer Line Vent

The sewer line vent is designed to carry sewer gasses out of your house each time you flush. This venting system typically runs behind your bathroom walls and up to the roof where it can escape into the air. 

If a clog occurs in this vent line, it can prevent adequate airflow and stop your toilet from functioning properly. If you think this might be the reason your toilet bowl has a low water level, call a plumber. Removing a blockage in a sewer vent line can often require access from the roof or an elevated external vent. 

7. Check Waste Pipe Joint For Leaks

If your toilet rocks or wobbles, there’s a possibility that the wax seal connecting your toilet to the waste pipe is leaking. If your toilet bowl moves and you have signs of leaking then it would be best to remove the bowl and inspect and replace the wax gasket.

If there is a broken, disconnected, or leaking pipe somewhere, your toilet may not fill or flush correctly, resulting in not enough water in the bowl. 

Water leaks in your home’s plumbing can be a challenge to diagnose, but some tell-tale signs that there is a leak include water marks appearing on the walls or ceiling and a musty, moldy smell that won’t go away. If you think there is a leak in your home’s plumbing, don’t let it go too long because a low toilet bowl water level will be the least of your worries. 

In this situation, it may be best to call on the assistance of a plumber to help you accurately identify the problem and offer the most cost-effective solution.

FAQ’s Why Is The Water in My Toilet Bowl Low

Can I add water to my toilet?

If the water level in your toilet is low, it is safe to add a small amount of water. You can add water by using a bucket or pitcher to slowly pour water into the bowl until the water level rises to its normal level. However, depending on the root cause of the initial problem the water level may simply drop again.

Why is the low water level in my toilet bowl making a gurgling noise?

When your toilet bowl doesn’t have enough water in it, the air in the pipeline can escape creating a gurgling or bubbling sound. A clogged vent stack or drain line could be another possible cause. This type of blockage can prevent air from escaping properly and cause gurgling noises.

Plumber and HVAC Technician | Website | + posts

As a retired Master Plumber Jamie has over 30 years of hands-on experience, making his plumbing knowledge second to none. He has also worked on both residential and commercial HVAC installation and repair projects.