Why Is My Toilet Not Filling Up with Water?

Whenever there’s a problem with the toilet, life becomes much more stressful until everything’s up and working again. You may say that this is an exaggeration, but properly working toilets are one of the things we take for granted the most as humans.

Think about a time when you really had to flush for a second time, but the toilet was not filling back up with water. Think about the anxiety. Do you still think we’re exaggerating?

Luckily, we have some easy-fix tips for this very common issue. Some of the fundamental parts of the toilet’s flushing mechanism may need to be fixed, cleaned, or replaced. Or some parts may be malfunctioning simply because they need readjustment.

Since you need to know what these parts are and what they do, let’s take a quick look at them.

How Flush Toilets Work: The Basics

Before you start trying out possible solutions, you may want to familiarize yourself with the inner workings of a toilet flushing system.

The modern flush toilet has two basic components, the reservoir and the water trap (also known as the U-bracket). The water trap acts as a seal between your bathroom and the rest of the sewage system by blocking the gases and odors from the sewer to which your toilet is connected.

The reservoir, on the other hand, is a water reservoir that holds a large amount of water and quickly releases it through the water trap. This large amount of water, which rushes into the toilet bowl rapidly, pushes everything from the water trap to the sewer by the force of gravity, leaving a clean body of water in the pipe waiting for the next visitor.

The secret of a successful flushing mechanism lies in the rapid discharge of large volumes of water into the toilet bowl. Anything that blocks or disrupts this water flow can cause your bowl or tank not to fill up properly.

Essential Parts of a Flush System

Now that you know the basic working principle of a flush system, it’s time to get into the specifics. These are the main parts of a flush system:

  • The handle or the trip assembly is the part that you press to initiate the flushing system;
  • The fill valve is used to fill the tank with water, and it connects to your water supply;
  • The flush valve releases the water in the tank into the toilet bowl;
  • The overflow tube is connected to the flush valve, and it drains extra water that may overflow the tank;
  • The flapper is connected to the handle and the overflow tube, and it’s usually a rubber seal that releases the water into the bowl when the handle is pressed;
  • The float is a ball or a cylinder that connects to the fill valve and controls the fill valve as it moves up and down with the water inside the tank.

Why Is My Toilet Tank Not Filling Up with Water?

Even though you might think that you’ll need a plumber to fix your flush toilet, the most common issues that cause a toilet bowl or tank to not fill up can actually be solved easily by yourself. We’ve explained how the flushing mechanism works and what the main parts are. Well, it really doesn’t get more complicated than that!

Now that you’re fully intellectually equipped to tackle your problem, let’s take a look at some of the potential culprits behind your toilet not filling up.

Check the Water Supply First

If your toilet tank is not filling up with water after you flush, you first need to eliminate the possibility of a water supply problem. If you’re sure there are no current problems regarding water supply at your house, there may be some very common causes of your problem. The first part you want to check is the flapper.

The Flapper May Be the Problem

The flapper is the part that seals the water in your toilet tank until you pull the handle and flush. When the handle is pressed, the flapper lifts, allowing the water to escape. If the flapper is not sealing properly after you flush, it might need to be replaced.

The flapper is usually connected to the handle with a chain. The problem also might be that the chain is too short, stuck inside the mechanism, or under the flapper itself. Before changing anything, make sure that this isn’t the case.

If the flapper is indeed the problem, you’re going to need to replace it. Here are some steps you can follow to change the flapper:

  1. Turn off the water supply;
  2. Flush to empty the water in the tank;
  3. Detach the chain that links the handle and the flapper from the handle first;
  4. Detach and remove the flapper from the overflow tube;
  5. Make sure you clean around the flap before you install the new one;
  6. Follow the same steps to attach the new flapper to its place;


Sometimes, debris buildup can happen under the flapper and inside the fill valve. Let’s take a look at what to do in case this happens.

Clean the Fill Valve

Another possible cause for your toilet tank not filling up can be the debris buildup inside your fill valve. To clean out your fill valve, you can try these simple steps:

  1. Turn off your water supply line;
  2. Take off the cap on top of the fill valve;
  3. Slowly turn the water supply back on a little bit, allowing the buildup to be released;
  4. Turn the water supply off again;
  5. Put the cap of the fill valve back on;

And then you can turn your water supply fully back on. You can add this process to your toilet cleaning routine every now and then if your water supply contains a lot of debris. To find out more about cleaning your toilet, you can read our article on cleaning a toilet the right way.

If this solution has not helped your case and the tank is still not filling up, you may need to replace the fill valve.

You can also replace the fill valve easily by yourself by following these simple steps:

  1. As always, turn off your water supply.
  2. Empty the tank by flushing the toilet.
  3. Usually, the water supply line is in the back of the tank. Using your hands, disconnect the water supply tube by turning it.
  4. Remove the nuts that hold the fill valve at the bottom and remove the fill valve.
  5. Clean the area and install the new fill valve following the same steps.
  6. Also, you can adjust the height of the fill tube to your toilet tank’s size by turning the top section.

Maybe It’s the Trip Assembly?

If the trip assembly, more commonly known as the handle, gets damaged or misshapen, your toilet may not fill with water properly. Check the handle mechanism to see if it’s bent or broken. If it’s bent, try to bend it back to its original shape.

If the trip assembly is bent too badly to be bent back or if it’s broken, you’ll need to replace it. Replacing this part is very simple as you only need to detach the old trip assembly from the flapper and install the new one in its place.

Readjust The Float

Another reason your toilet may not be filling up with water may be due to the float not working properly. As we’ve already explained, the float is a ball or cylinder that drops to the bottom of the tank when the water is released, pulling on the fill valve to refill the tank.

If the float is not working properly, your tank may not fill back up, even if there’s nothing wrong with the tubes, valves, or pipes. By readjusting the float, you can increase or decrease the amount of water you want your tank to be filled with.

Here are some easy steps you can follow to readjust the float in your toilet:

  1. As always, start by turning off the water supply.
  2. Empty the toilet tank by flushing it.
  3. If your toilet is an older one, the floater will be a ball. Find the screw that connects this ball to the fill valve and turn the screw using a screwdriver to adjust the height of the water.
  4. If the float is a cup or cylinder shape, locate the long plastic bolt that is attached to the floater and turn it with a screwdriver to adjust the height of the water.

Another reason your toilet tank may not be filling up with water is that the float may be touching the sides of the tank and getting stuck. If the float is held up and can’t drop to the bottom of the tank, the tank won’t fill back up.

If the floater is broken or the chain that connects the floater to the fill valve is disconnected. You can simply replace the chain or reattach the float to make your toilet functional again.

Check Your Bowl For Cracks

Lastly, if your toilet is leaking due to a crack, this may be another reason your toilet bowl may not be filling up with water properly. Check thoroughly around your toilet to see if there are any puddles of water. You may not be able to realize for a while if the crack is in the back of the bowl.

A cracked toilet bowl can be dangerous and needs to be replaced. It is not recommended to use a cracked toilet as it can break while you’re using it, and it can also cause flooding in your bathroom.

To prevent potential disasters, if your bowl is not filling up with enough water, make sure you check your bowl for cracks and replace the bowl if that’s the case.

To find a solution for other potential problems regarding your toilet, you can read our article on the common problems with toilets and how to fix them”.

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