Why is my toilet bowl empty – Master Plumber Explains

Toilets! We all have them and use them daily. However, sometimes we are faced with these strange situations where we find our toilet bowl dry and wonder where the water went.

In some cases, you may find that your toilet bowl empties itself occasionally, even without your intervention. In such cases, it becomes extremely hard to investigate why your toilet bowl empties sometimes, whereas other times, it works perfectly fine for weeks, and sometimes even months.

So, why is your toilet bowl empty? Your toilet bowl is empty because of a crack in the bottom of the bowl that is letting water escape. It may also be due to a poorly sealing toilet flapper that is allowing the water to slowly drain away.

David Parker, a master plumber with a master PI License for the states of North and South Carolina, also adds that your toilet may be empty because of damaged flappers. He argues that damaged flappers do not seal properly, allowing water to empty from your toilet bowl.

Why would a toilet bowl suddenly empty?

Chances are you have started noticing your toilet bowl emptying suddenly, and this is frustrating you. Unfortunately, toilet bowls emptying suddenly and randomly is a widespread problem that many people deal with daily, where they go to bed with the toilet bowl looking normal with water, and wake up to an empty bowl, and they must refill it again to use the toilet.

Here is a video that explains how to fix a toilet bowl that has a low level of water:

If you start noticing that your bowl is emptying suddenly, and the problem starts to become persistent, here are some of the reasons why that may be happening to you.

  • Cracked toilet bowl

Your toilet bowl may be cracked at the bottom. These cracks are usually hard to see, and the way the toilet bowl is laid out, water runs under the bowl, and when the bowl is cracked, the water drips into the trap, resulting in the emptying of the toilet. This is also one of the hardest causes of empty toilet bowls because when it happens, water does not leak onto the floor, and hence there is mostly no indication that the bowl has cracked on the inside.

  • Clogged vent

Clogged vents are also a major reason your toilet bowls may be emptying. Vents are a vital part of your drainage system and run to the exterior out of the roof, where they supply your drain with air for it to work properly. They are connected to your plumbing system and rise to the roof or connect to a pipe that runs to the roof. When clogged, a flushing action results in water being sucked out of the trap to satisfy air demand resulting in empty toilet bowls.

  • Damaged flapper

Flappers allow the water in your toilet bowl to stay thereby sealing the tank. During flashing, flappers allow water to move from the tank to the toilet bowl.

Here is a table that highlights what forum visitors tried to unclog a toilet that had a block causing the bowl to totally drain:

How to unclog a toilet that is draining totallyPercentage of total results
Buy an auger and dislodge the clog in the toilet to get rid of the vacuum in the bowl that is emptying it. I recommend a Drainsoon Auger that is available on Amazon. 38%
To unclog the toilet, turn off the water, empty the bowl and then add a bottle of vegetable oil. Turn back on the water and flush it a few times. 25%
For a partial clog, use a plunger after adding more water. Plunge five times before flushing again. I recommend the plunger by Yanxus since it comes with a caddy that hides it from sight. Click to view one on Amazon.31%
Turn off the water supply to the toilet, add a bottle of dish soap and then flush. This causes the clog to dislodge allowing the toilet to function correctly. 6%

What causes a toilet bowl to slowly drain?

Toilet bowls can start draining slowly, signaling a problem in your drainage system. When that happens, finding the root cause of the problem is always paramount and can help you fix the problem fast, and avoid extra plumbing expenses when the slow draining persists, and you must call a professional plumber to fix it.

If you notice that your toilet bowl is draining slowly, chances are your toilet is experiencing one of these problems.

  • A clog in the drain line and vents

Vents are responsible for allowing air to enter your drainage system and to allow water to flow downwards. They also release gases and smells from your house, preventing bad smells from building up in your house. However, when damaged or clogged, it can lead to a reduction of air into your drainage system, and hence reducing their ability to pump water downward, resulting in slow drainage in your water bowl. Fortunately, the process of checking your sewer vents is easy, and you can also opt to call a professional to check your sewers.

  • A damaged connection between the tank and toilet bowl

It is not always that the problem with your slow drainage system is because of the bowl and the drainage line. Sometimes it can be because of your connection between the tank and the toilet bowl or a blockage in the inlet hole. This results in flushing water seeping much slower, which can result in a slow drain of your toilet bowl.

  • Low water levels in the toilet tank

If your toilet tank has a low fill level, it can result in a slow drain of your toilet bowl during flushing. This can be caused by several factors that are mostly beyond our control, and the solution is to call a plumber or maintenance to help address the problem.

  • Rim having a mineral and sediment build-up

The build-up of minerals and sediments along the sides of holes can result in low pressure, which causes slow drainage of your toilet bowls.

What can I do if there is not enough water in my toilet bowl?

Finding there is no water, or sometimes the water available in your toilet bowl can be frustrating. However, knowing the root cause of the problem can provide insights into how to solve the issue. Below is a list of reasons why your toilet bowl may be having a low amount of water:

  1. The refill tube is damaged: The refill tube connects the vertical, wider plastic tube of your toilet, commonly known as the overflow tube, with the tank. It is responsible for getting water from the toilet tank to the toilet bowl. When damaged, it prevents water from flowing to your toilet tank and toilet bowl, resulting in an empty toilet bowl. This can be resolved by replacing the fill tube. Luckily, they are easily available at the hardware store, and you can easily do it yourself.
  2. Cracked toilet bowl: You may start noticing spillage of water in your bathroom, combined with water levels on your bowl being low. This may be because of a cracked toilet bowl. Unfortunately, there is no easy solution to this problem, and you will need to replace your toilet. This will include the costs of a professional plumber who you will call to install the new toilets.
  3. Blocked sewer vent: Sewer vents remove sewer gases and allow air to flow into your drainage system, thereby allowing water to flow downwards. When damaged or blocked, the vents can result in a shortage of free flow of air, resulting in little or no water in your drainage system, and your toilet bowls. The solution to this problem is climbing onto your roof and unclogging the vent system. A safety note you should always keep in mind while performing this task is, if it looks unsafe, it is advisable to consult a professional.
  4. Fill valve may be damaged: Fill valve regulates water flow in your bowl, and if it is damaged, it can result in a low amount of water in the toilet bowl. The solution is the replacement of the fill valve. Luckily, the replacement is not complicated, and chances are you will be able to replace it with no problem.

What keeps water in a toilet bowl

Have you ever asked yourself how a toilet is able to keep a certain amount of water in the bowl, even after flushing? Well, if you have, you may be surprised to find out that the process involves a lot of physics and pure mechanical works to achieve this.

For starters, the first you thing that you see when you look at a toilet is a waste pipe going through the floor and a tank of water up above. The tank of water is referred to as cistern, and contains water that is flushed when a lever, a button or a chain is pushed or pulled.

For most toilets, the process of flushing the toilets is purely mechanical, as explained by Brad Holden, a plumber with over 30 years of experience, who indicates that the process involves pulling the lever to allow water to empty from the cistern through the force of gravity. The water drains into the toilet bowl and cleans it for use again. This usage of levers also determines when to flush (during pulling of a lever) and when to fill the cistern again (after it is emptied while flushing). This process is what scientists refer to as simple machines.

However, the process is more complicated than it appears at first glance. When you flash a toilet, the cisterns have to automatically refill again up to a level where the tank is just full enough with no overflow.

Now let’s talk about the little water that is always left on the bowl even after flushing. This is the water that is always trapped in a large S-bend pipe of the toilet bowl. The water is used to seal off the sewage pipe beneath it and stop germs and bad smells from coming up into your bathroom.

The S-bend pipe allows the pipe running out from the toilet bowl to curve upward before curving back down again. This allows the water flowing into the bowl from the cistern to drain out through the pipe with enough momentum to produce a siphon effect, which properly empties the bowl. It also ensures that some water remains at the bottom of the bowl, which improves hygiene.

My toilet bowl is empty, but the tank is full

Your toilet bowl can start to empty suddenly, even in cases where your tank is still empty. Luckily, this problem is not uniquely yours alone, and many people who have experienced such problems in the past have also offered insights into what might be wrong with your toilet bowl. Below are some of the reasons why your toilet bowl is empty, but the tank is full.

  1. Your toilet bowl is cracked: Unfortunately, this is among the top reasons why bowls start losing water, even when the tanks is full. The problem is also complex because, when the bowl cracks, water does not leak on the floor, but instead drips into trap, and hence making the problem hard to diagnose.
  2. You may be having damaged flappers: If flappers are damaged, the water in your water tank is not able to move to your toilet bowls during flashing. The result is that your tank will always be full, but your toilet bowls will not have water.
  3. Clogged vent: Vents play an important part in your drainage system, by allowing air to enter the system, thereby allowing water to move downwards. When they are damaged, the air is prevented from getting inside your drainage system, and water in your toilet bowls may be sucked up or down, resulting in the emptying of your toilet bowl. In most cases, when this happens, the water in your tank is not affected, hence you will start to notice that there is water in your tank, but no water in your toilet bowls.

Why does my toilet randomly empty itself?

You may start to notice that your toilet randomly empties itself, even without your input. When this happens, in most cases, the problem is with your vents.

Vents play a key role in your drainage system, by supplying air to drainage pipes. When blocked, frozen or damaged, this is no longer possible, and the result is the air supplied to your pipes may not be enough. This causes your pipes to suck water up, and sometimes down, resulting in your toilet emptying itself even in situations where flushing has not been triggered.

Another reason your toilet may be emptying itself is that, without a vent, the air in the system can only escape through the sewer. As the air tries to escape through your sewers, the waste and water trapped in your bowl and tank are pulled into the trap of the toilet with it. The result is that the toilet empties itself, without any input such as a flushing action.

Related Articles:

If your toilet is making a lot of strange sounds, the article on why does my toilet whistle will be helpful. Also why is my toilet loud is another helpful article.

Besides having the problem of a toilet that is emptying on its own, you may wonder why is my toilet water yellow all the time.

Aron Blake

I am the lead copywriter on Homezesty and the Webmaster. I have a lot of experience in home renovations and the creation of style. I enjoy writing and sharing my tips on how to create the best living environment. My Linkedin Profile, My Twitter Account

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