5 Reasons Your Toilet Bowl Water Is Low (and Possible Solutions)

Allie Ogletree
Written by Allie Ogletree
Reviewed by Jeff Botelho
Updated February 10, 2022
Modern bathroom sink, toilet, and shower
Photo: Iriana Shiyan / Adobe Stock

Fix your toilet’s flow with a few simple solutions

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Let’s face it: It’s a dreaded experience to see your toilet flush, only for the water to stop short of filling up the bowl. This seemingly minor inconvenience can actually feel like a major hassle, especially if you cannot fully flush the toilet. Thankfully, there are five main reasons why your toilet bowl is low, many of which have some simple fixes.

Before you get started:

First and foremost, make sure that the water in your bathroom is on and working properly. If there is an issue with the water supply to that part of the house, then this step will help you easily narrow down the source of the problem.

Also, check to see if something has accidentally triggered the shut-off valve on your toilet, as this would mean that your toilet has no access to water.

If the water supply is running accordingly and the shut-off valve is off, then you’ll want to proceed to the following solutions.

1. There’s a Problem With the Toilet Tank

One of the easiest problems to fix is a lack of water in your toilet tank. Numerous things can cause this common toilet repair problem, most of which involve the toilet fill valve or flapper. 

The fill valve, also known as the ballcock, controls how much water fills the tank. If the mechanisms are misaligned or broken, the toilet tank won’t fill to the correct amount. When this happens, the tank water level can be too low to fill up the bowl. 

Similarly, if there is a problem with the flapper that drains the water from your toilet tank to the bowl, then you might also experience low water levels in the basin. 

How to Fix the Toilet Tank Mechanisms

There are two main ways to fix a toilet with a toilet tank that isn’t working properly: adjust the toilet fill valve or replace the broken parts. You can figure out which option you need by removing the cover to your toilet tank and inspecting the tank. 

The first thing you’ll want to do is inspect the fill valve and flapper to see if there is a worn or broken component. If all looks good, you can adjust the fill valve to see if that solves the problem. Depending on the type of toilet you have, the fill valve mechanics may work differently, so check the manufacturer’s manual when inspecting your toilet. 

If adjusting the valve doesn’t work or you notice a broken valve or flapper, you can usually repair the toilet yourself with a DIY flapper fix. Oftentimes, a quick trip to the hardware store and the right replacement parts will do the job.

2. You Have a Partial or Full Clog

Another cause for low toilet bowl water is the classic clog. The most common type of clog is one in the internal piping of your toilet that often causes a toilet to overflow. In some cases, however, the blockage siphons water out of the toilet bowl, causing low water levels. 

If a partial clog is causing your toilet’s low water levels, one of the best ways to tell is by observing how the toilet flushes. If the water levels rise to the top of your toilet only to slowly go down until water levels are below normal, chances are this siphoning issue is somewhere in the trap of your toilet.

How to Fix a Partial or Full Clog

You can fix this issue by removing the blockage. Use a gloved hand, toilet plunger, or toilet auger to remove the obstruction. If you suspect that there is a blockage deep within the pipes, you may need to contact a professional plumber near you to remove the object.

“As a plumber myself, my personal recommendation for clearing a clogged toilet is to skip all other steps and go straight for the closet auger (toilet snake),” says Jeff Botelho, Angi Expert Review Board member and Massachusetts-licensed journeyman plumber. “This is because most people end up causing more problems than they solve by using plungers improperly.

“Contrary to popular belief, the plunger is NOT meant to force a clog down the drain. Plungers are meant to be used to create suction in the toilet trap, causing the blockage to break up and then flow down the drain when the plunger is pulled out of the bowl. Pushing hard on a plunger usually just blows out the wax seal between the toilet and the flange. Then the toilet has to be pulled and resealed.

“A closet auger is a much more effective and efficient way to remove a blockage from the trap because it uses a cable to break up the clog and allow it to flow out of the toilet. Like any other tool, it is important to learn how to use it properly but it’s a lot harder to cause a leak by improperly using a closet auger than it is with a misused plunger."

Plumber fixing the tank of a toile
Photo: New Africa / Adobe Stock

3. You're Dealing With Clogged Inlet Holes

Another cause of low water in a toilet bowl is due to clogged inlet holes. Also known as rim jets, these holes can be found just under the rim of your toilet. Depending on the type of toilet and the quality of your tap water, the water draining from the tank into the bowl can calcify and become plugged.

How to Fix Clogged Inlet Holes

The best way to fix a clogged inlet hole is by carefully adding hot vinegar into the tank via the overflow tube. You’ll want to let the vinegar soak for a good couple of hours to help dissolve calcium deposits.

Simply use a toothbrush to scrub away the deposits or, if they’re compacted, poke a small wire inside the holes to clear them out (the end of a wire coat hanger is perfect for this, says Botelho). Then, flush the toilet to see if this trick did the job.

4. There’s a Blockage in the Vent Pipes

Plumbing vents, also known as sewer vent pipes, allow sewer gases and oxygen to flow out and into the waste pipes, respectively. If your plumbing vent pipe is blocked, then the pipes will search for another outlet within your home to access air. When this occurs, toilets make loud, gurgling sounds as the vent pipe siphons both water and air. 

A blocked vent pipe often occurs on the roof of the house, where the vent is typically located. Anything from bird nests to leaves can obscure the ventilation, leading to a blockage. Sometimes, even windy days affect the water levels of your toilet because of the vent system.

How to Fix a Blockage in the Vent Pipes

You need to clear the debris in order to allow the air to flow freely within the ventilation system. To prevent animals and plants from blocking the airflow in the future, you might also want to invest in a vent cover. However, you should never attempt to get up on the roof yourself, so this is a job for a pro.

5. The Toilet Bowl and Pipes Are Cracked

Lastly, if you notice a crack in your toilet bowl, trap, or any associated pipes, then you need to replace them. Find a toilet repair pro near you, or contact your trusted, local plumber to install or repair the broken parts. 

Remember: While most small toilet issues are somewhat easy to resolve without a professional, if your DIY repairs don’t do the job, then you’ll need to check with a professional and factor in the cost to repair your toilet.

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