7 Reasons You Have Low Water in the Toilet Bowl (And Possible Solutions)

It’s a dreaded experience to see your toilet flush, only for the water level to stop short of filling up the bowl. This seemingly minor inconvenience can feel like a major hassle, especially if everything seems to be working correctly on the outside. There are seven main reasons why you might have low water in the toilet bowl, and thankfully, most have simple fixes.

1. Make Sure the Water Supply Is On

Before calling a local toilet pro to fix your low water in the toilet bowl problem, make sure that the water in your bathroom is on and working properly. If there is an issue with the water supply to your toilet, the water in your toilet bowl will be low and won’t fill until this problem is solved. Thankfully, it’s often a simple fix.  

How to Fix the Water Supply 

The water supply valve for your toilet is behind it and should be fully turned counterclockwise to the “open” position. If it was closed for whatever reason and you’ve just reopened it, give the toilet a flush to see if that fixed the low water problem. 

If the valve is fully open and you’re still having low water in your toilet bowl, you might have another problem with an easy solution. 

2. The Toilet Tank Isn’t Filling Properly

One of the most common causes of low water in your toilet bowl is a lack of water coming from the tank. Luckily, it’s also one of the easiest problems to fix. 

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 toilet flapper that drains the water from your toilet tank to the bowl, then you might also experience low water levels in the basin. You can try adjusting the water level in the toilet bowl to get it back to normal.

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 or replace the toilet fill valve. 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.

3. The Water Evaporated

No, your eyes might not be deceiving you. If you live in a particularly hot climate or have left your toilet seat open and gone on a long vacation, the toilet water in the bowl could have evaporated, leaving you with lower levels than usual. While not overly common, this can happen, and while it might not seem like a huge deal, it could cause a smelly situation.

How to Prevent Toilet Bowl Water Evaporation

It’s important to note that the evaporation of toilet bowl water, which in turn leads to low water levels in the toilet bowl, does not happen overnight—this process happens gradually. To prevent it from becoming an issue, make sure to regularly flush your toilet to maintain the correct water level (this is especially important for those secondary bathrooms that are often forgotten about). 

If you’re going to be away from home for a long period of time and live in a dry climate, make sure you give your toilet one final flush and close the toilet bowl cover to limit air exposure to the water.

4. You Have a Partial or Full Clog

Another cause for low water in the toilet bowl 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 drain slowly 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.

5. You're Dealing With Clogged Inlet Holes

Another cause of low water in a toilet bowl is 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 to carefully add hot vinegar to the tank via the overflow tube. You’ll want to let the vinegar soak for a 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. Then, flush the toilet to see if this trick did the job. If you suspect that this is the reason for your low water level but the solution did not work, call a plumber near you to further investigate. 

6. 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. Before pulling out the ladder, call in a toilet pro near you to confirm that this is the actual problem—you might save yourself some time and hassle. 

7. 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 to install or repair the broken parts. Depending on the extent of the problem, you may also want to file an insurance claim for water damage that results from the broken pipe, and it’s not a bad idea to check for mold in the affected area.

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.