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8 Causes of Low Water Level in Toilet and How to Fix It 

Low toilet water can be just as annoying as brown toilet water, or a toilet that won’t stop running. It can quickly add another headache to your list of daily tasks, and it may take a while to uncover its causes. 

Since there are 8 (or perhaps even more!) reasons your toilet water may be low, take a look at this list, and try to determine what the most likely culprit is. 

In a nutshell, your toilet water can be low if you have a damaged tube or valve somewhere, if the bowl is cracked, if there is something wrong with the toilet tank, or even if you have a clog somewhere in your pipes. 

Here are all of the 8 causes of low water level in your toilet outlined for you: 

1 – Damaged Fill Tube 

One of the most common reasons your toilet bowl water may be low is damage to the fill tube. It’s a small plastic hose located in your toilet tank and it allows the water to flow into the bowl every time you flush. 

Over time, it may unhook itself from the overflow tube it is connected to, it may start to leak or get damaged in other ways. This may be causing the fill valve to shut off water flow before the bowl is actually filled. 

To test if this is the cause of your low water level, lift the lid off your toilet tank and check the fill tube. If it seems okay and well connected to the overflow tube, it’s probably not what’s causing your issue. You can also try re-adjusting it or replacing it. 

2 – Damaged Fill Valve 

The fill valve is also located in your toilet tank, and its job is to refill the tank after each flush. It’s usually a white tube connected to your water supply at the bottom of the toilet, and it has a valve you can shut it off with at the top. 

Your float will float (pun not intended!) to the top of the tank and shut this valve off once the water has reached the right height. If your fill valve is not working, it may stop pouring water into the tank sooner than it should.

Check your fill valve to make sure it’s not too worn out. You can easily buy a replacement at your local hardware store (just make sure you get the dimensions right). 

3 – Your Toilet is Clogged 

While most people associate clogged toilets with overflowing, a clog might actually be siphoning off the water from your bowl. 

The way to check for this is to watch the toilet as you flush it. If the water rises too high and then slowly drains to your low water levels, a clog is the likely culprit. 

Clogs can be caused by flushing things that are not meant to be flushed. You can check out our list of non-flushable items to see if you may have inadvertently created a blockage you now need to remove. 

While a toilet may unclog itself with time, you will likely need to take matters into your own hands. You can use a plunger, a toilet unclogger or a plumbing snake, or you may call your plumber to help. 

4 – Your Inlet Holes are Clogged 

Inlet holes (or rim jets) are the holes under the rim of your toilet that release the water when you flush. If you live in an area with hard water, limescale may start to develop here and clog these holes, leading to the low level in your toilet bowl.

What you will need to do is clean below the toilet rim and remove this buildup of limescale. You can either use a commercial product, or mix your own with baking soda and vinegar. 

Use this time to clean your toilet below the waterline as well, and remove the limescale buildup there too. 

5 – Blockages in Your Sewer Vent Line 

If there is an issue with your sewer vent line, you may be seeing low water levels in your bowl. This is rare, but it could happen. 

Your sewer vent line runs through your bathroom wall outside through your roof, and it removes sewer gasses and oxygen when you flush the toilet. If there is no proper air flow, you could start to see some issues. 

What could be blocking your sewer vent line? Well, it might be some leaves or branches, or a bird may have decided to make its nest up there. There could also be something dead in there. 

The solution to this issue is to clean your roof and check the sewer vent. If you see a blockage, try to remove it. However, you are advised to recruit the help of a professional plumber for this endeavor. 

6 – Damaged Toilet Handle 

If your toilet handle is damaged, it may not be releasing enough water into the bowl from the tank. If your handle is broken or missing altogether, this is likely the case. 

While you can still flush your toilet without a handle, you should fix it as soon as possible, to ensure it has enough power to pull the flapper all the way up, and release enough water. 

7 – Cracked Toilet Bowl 

If your toilet bowl is cracked, water will seep out of it and the water levels in the toilet will be low. The simplest way to determine if this is the case is to see if there is any water (or water stains) on the bathroom floor around the toilet. 

You may be able to seal your cracked toilet, but the best course of action will be to replace it. Bear in mind that cracks in toilet bowls are rather rare, so this may be the least likely reason for your low water levels. 

8 – You Have a Thirsty Pet 

Believe it or not, pets will drink from a toilet bowl on a regular basis. While dogs are the likelier culprits than cats, even they can be caught taking a sip out of the bowl.

If you have a pet, check your toilet water levels when you flush, and prevent your pet from accessing the bathroom for a couple of hours. If the water level remains the same, you can repeat the experiment a couple of more times before you let them back in. 

Or, you can install a camera to keep an eye on your pets’ bathroom habits, and score yourself some laughs in the process. 

How to Prevent Low Toilet Water Levels

The best way to prevent low toilet water levels is to keep your toilet tank and toilet as clean as you can, and regularly check that all the parts are working properly.

Valves and tubes will naturally decay over time, so you will need to replace them. Remember that toilet tanks are not universal, so you will need to find parts that work in your specific model. 

Clean your toilet regularly (this includes under the rim), and make sure you never flush anything other than pee, poop and toilet paper. Never flush condoms, don’t flush paper towels, and make sure you don’t flush tampons even in an emergency. Hair should not be flushed either, as it can cause a clog over time. 

Wrapping It Up 

Low water level in your toilet can be highly annoying, but it may be an easy fix. If you are unsure as to its cause, call your local plumber in to help you discover it and eliminate it as quickly as possible. 


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