Why Does the Water Level in the Toilet Bowl Keep Dropping?

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Do you feel like the water level in your toilet bowl keeps getting lower every day? If yes, you need to take action because the toilet may stop working soon.

Many homeowners deal with the same issue and keep asking us how to increase the water level in their toilet bowls. Fortunately, all you need is the basic knowledge of toilet functioning and some elbow grease.

This article will explain the roots of the problem and a couple of ways to fix it.

What Makes the Water Level Drop?

Toilets are complex structures with parts like an internal P-trap. Still, only a couple of elements can cause the water level in the bowl to decrease.

Cracks in the Toilet Bowl

If your toilet bowl has even a hairline crack, it can cause a leaking toilet.

In this case, water from the toilet bowl will appear on the floor — you will notice it around the toilet and figure out the problem instantly. However, you may also check it to make sure there are no surface leakages.  

The test is simple — put dry towels or toilet paper around the bowl and don’t use your toilet for an hour or two. If you don’t see watermarks on your towels, there are no surface leakages.  

Another option is that water goes down the drain. This prevents you from seeing the water coming out of the cracked bowl and onto the bathroom floor.

Clogs in the Vent

Clogs in the vent system are the second factor that makes the water level drop in your toilet bowl. If you press the flush valve, the water goes out of the bowl through the drains. The water leaves a vacuum seal in the drain, so the vent lets air in to balance the negative pressure.

When the vent is blocked, there is not enough air to fill the vacuum and pull fresh water back to the bowl. The toilet cannot work properly as it won’t be getting enough water to fill the bowl and throw out the waste the next time you flush it. 

How to Determine the Cause of Low Water Level in Toilet Bowl?

The critical question is: How do you know if your toilet bowl has cracks or a clog in the vent?

A quick test is to turn on all faucets and listen to the sound of water. If you hear gurgling, the problem is the air vent. But there is another, more time-consuming test.

Close all faucets in your home to prevent water from going down the drains. Now you should fill the bowl with water to test it for leaks — pour until it reaches the average level.

The next task is to mark the water level on the toilet bowl with a tool like a permament marker. It’s a waterproof pen for multiple purposes, so you can successfully mark the water level on the toilet bowl. It will help you determine whether the water is leaking out or not.

Now you need to wait for a while and let the toilet bowl rest. Don’t touch anything for at least a couple of hours because that’s how long it takes for the water for the tiniest cracks to start releasing water.

Finally, you can check the water level in the toilet bowl. 

If it’s below the mark, you have a leak — cracks let the water escape to the bathroom floor. If you don’t see puddles anywhere around the bowl, it means that the water flows into the drains.

Replace the Toilet Bowl to Increase Water Level

Now that you know why the water level in the toilet bowl keeps dropping, you can start fixing the problem. You can either change the toilet bowl or clean the blocked vent.

Here’s how you can replace the cracked toilet bowl.

Step 1: Close the Water Supply Line

You must close the water supply first because it allows you to work without getting wet and dirty. The shutoff valve is almost always on the wall behind the toilet or in its closest proximity. Turning it off is simple — twist the knob clockwise to close the water lines. 

Step 2: Empty the Toilet

DIY bathroom projects are always messy, but you can minimize the damage by emptying the toilet. Press the flush handle and water will go from the tank down the drains.

You can also open the tank lid to remove excess water — take it by the edges and lift it. Use a dry towel or toilet paper to collect the remaining water droplets from the tank and its overflow tube.

After that, you should use a plastic cup and a sponge to remove water from the toilet bowl. Once the toilet is empty, you are good to go to the next stage.

Step 3: Remove the Water Supply Hose and the Toilet Tank

To remove the bowl, you also need to disconnect the water hose and the tank. The metal hose goes from the wall to the tank, which is where you should detach it. Use a pair of pliers to unscrew the nut connecting the hosepipe to the tank. 

When you do it, you can also detach the tank. You will see a couple of bolts and nuts on its bottom, so use the same pliers to turn the tank nuts counterclockwise. Turn the nuts until it’s easy to remove both bolts with your own fingers. 

Step 4: Remove the Existing Bowl

Now the toilet bowl is ready for removal. At its base, you’ll see a pair of bolts keeping the bowl firmly against the ground — remove the plastic caps covering the bolts using a flathead screwdriver or a utility knife. 

After that, you can unscrew the thread nuts surrounding the bolts. Turn them counterclockwise until they are loose enough to let the bolts go out of the hole. Our advice is to use an adjustable wrench for turning the nuts. 

When you unscrew the bolts, you can grab the bowl and remove it from the floor flange and wax ring.

Step 5: Set the New Bowl

Finally, you can repeat all these steps in reverse. Set the new bowl to the flange and tighten it with toilet bolts — turning the thread nuts clockwise will do the trick.  

After that, you can re-install the other elements: the tank and the hosepipe. Once again, turn the nuts clockwise to secure the tank bolts and set the tank. When you do that, remember to attach the supply hosepipe to the tank. 

Finally, you can open the water supply valve and wait until the tank is full again. The water level is now sufficient to flush the toilet and leave enough water in the bowl afterward. 

Increase the Toilet Bowl Water Level by Cleaning the Air Vent

If the problem is not in your bathroom throne, the only option is to clean the air vent. This task is even simpler than the first solution:

Step 1: Climb the Roof

Unfortunately, the air vent is on the roof, and you’ll have to climb there. This job is not for everyone, so be careful and find a safe position to work from. We recommend using ropes to secure yourself even in the worst-case scenario.

If you don’t feel comfortable working on such height, perhaps you should think about calling a professional plumber — they have much more experience unclogging air vents while working in a safe environment.

Step 2: Clean the Entrance of the Vent

The vent entrance is usually dirty, thanks to exterior materials and debris. Birds can bring all kinds of stuff to create a nest, while nearby trees can also block the air vent. Your job is to find a piece of wire to break through debris and open the vent.

A simple solution is to use a metal coat hanger — twist it with pliers until the wire becomes straight and long. After that, it’s easy to break through the air vent clogs by pushing the wire down the pipe. 

You can bend the wire at the end to form a hook. It will make the tool more efficient, especially when you pull it out. 

Step 3: Pour Water Down the Vent

Now you can pour water down the vent. Use a long garden hosepipe to reach the roof and turn it on — the water should break the remnants of the clogs and reach the drainpipe. 

However, remember not to use the maximum pressure when doing this. If the clog remains unbreakable, the water will return and backfire. That’s not what you want to deal with, particularly when working on the roof. 

Step 4: Use a Cleaning Pipe to Break the Clogs

If pouring water doesn’t help, you can use a toilet auger or a long pipe cleaner. It’s a 60-inch tool that easily runs through the air vent, while it can also penetrate curved pipes and sharp angles. 

The pipe cleaner has a two-inch brush at the end, which makes it perfect for breaking stubborn clogs and cleaning the pipe along the way. You must push it down the air vent slowly and then remove it to dissolve debris. The pipe cleaner will help you drill through the vent and resolve cracks with ease.

Step 5: Pour Some Water Again

The last task is to pour some water down the vent again — it will show you whether the tube is clean or not. If the water doesn’t backfire, you will know that the air vent is open. The last step should be a formality if you already drilled the hole with the pipe cleaner. 

The Bottom Line

Do you still think increasing the water level in the toilet bowl is difficult? With our instructions, we are sure you can do it quickly!

Remember to follow these steps when the water level in the toilet bowl keeps dropping:

  • Determine the cause: A clogged vent or a cracked bowl
  • Fix the problem: Replace the bowl or unclog the vent


What is the appropriate water level in the toilet bowl?

The standard water level in the toilet bowl is between 1.5 and 2 inches. If it goes below that, your toilet will start malfunctioning, and it won’t be able to flush out the waste.

Why is my toilet gurgling? 

If your toilet gurgles, there is probably a block in the vent. Instead of flowing through the waste pipe, the air goes back to the toilet bowl and produces a bubbling sound when flushed.

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