Why Isn’t My Toilet Filling Up? [Find out the Problems & Solutions]

Why isn't my toilet filling up

When you flush the toilet, the water tank should fill up within 10 seconds. It is a regular system. But, sometimes the toilet isn’t filling up with water after flushing. Or, after flushing the toilet, the water tank filling-up slowly.

So, why isn’t my toilet filling up? There are many things that happen here. The main culprit is the toilet fill valve. When this valve is damaged, your toilet is unable to fill up water on the tank. Moreover, misadjusted float arm or ball, low water pressure, damaged toilet bow, rusted overflow toilet water pipe, and others are also causing the problem.

Let’s find out the problems in detail and also fix the problem as soon as possible. Keep reading.

Why Isn’t My Toilet Filling Up?

The toilet needs to fill up because of several reasons. It is tricky enough to find out all of the problems. So, I will share with you some main reasons that don’t help the toilet tank fill up water.

Misadjusted Fill Valve

Most of the plumbers find misadjusted fill valve problems. They thought that the toilet wasn’t filling up because of a faulty fill valve.

How does a fill valve work? The fill valve provides a signal of the toilet when you press the flush button. It takes a maximum of 10 seconds to fill up the tank with water.

The fill valve is affected by a clog, rust, and some other problems. To fix this problem, you should complete a simple process which you will find in the following section.


  • If your fill valve comes with a screw on the top, you can use a flat-head screwdriver to remove the valve. Turning the screw clockwise to remove the valve.
  • Or, if the toilet tank comes with adjusted cylinders, remove the toilet cap lid and valve, which you find on the left side of the tank.
  • After removing the valve and cap, you should clean them properly. If you find them corrosion and extreme rust problem, it would be better for you to use a new one.

Low Water Pressure

When your toilet flush system is unable to create enough pressure, the toilet tank is not filling up with water. Low pressure mostly occurs because of blockage or leak in your interior plumbing system.

So, what can you do when your toilet comes with low water pressure? You should solve the problem without much delay.


To solve low water pressure, you should solve blocking and leakage problems. Well, to solve the blockage problem, you should check out the waterline pipe. Clean the waterline properly to solve the blockage problem. If the pipe has a leaking problem, replace it or repair it.

Damaged Toilet Bowl

This is another problem which doesn’t help the toilet tank fill up with water. A cracked toilet bowl with a slow leak can keep your toilet from filling up water.

You can look at the floor to find out about this problem easily. Why? Because a leak or cracked toilet bowl drops water on the floor.


You must first stop the main water line to fix the cracked toilet bowl problem. Please find out the damaged areas of the bowl and repair them. If it is completely cracked and hard to repair, you should purchase a new toilet bowl and replace it with your old toilet bowl.

Water Pipe Problem

A water pipe is a major problem that won’t help the toilet tank fill up with water. Users try to avoid checking out the pipe because of the complicated system.

But, if your toilet comes with a waterline or water pipe problem, you have to fix the problem. So, how can you fix the waterline or water pipe problem so that your toilet filling-up water?


First of all, you need to check out the beginning waterline or water problem. Gradually, you need to check out the whole pipe. If you find clog, rust, or other problems, you should remove them. Or, if the pipe comes with a leakage problem in multiple areas, buy a new water pipe to fix the problem.

Worn-Out Flapper Valve

Typically, the flapper valve is a rubber valve, which you find on the bottom side of your toilet tank. It helps the tank fill up with water and doesn’t empty the tank.

Sometimes the flapper valve is worn-out and doesn’t help the toilet tank to fill up with water. So, check out your toilet flapper valve. If you find the flapper worn out, you should buy a new flapper valve and replace it with the worn-out flapper valve.

FAQs (Frequently Ask Questions)

Q: How to fix a slow filling toilet tank?

Answer: First and foremost, you should find out the actual problems. Most of the time, the toilet tank fills up slowly because of filling valve problems, flapper valve issues, low water pressure, and so on. Check out the above-detailed answer and solution to fix the slow-filling toilet tank problem.

Q: How long should a toilet take to fill?

Answer: The standard time to fill up water in a toilet needs 10 seconds. But, some of the toilets also need to take a maximum of 3 minutes to fill up. Based on the toilet and some of the factors, the toilets take time to fill up water.

Q: Why is my water tank not filling up?

Answer: Your toilet tank needs to fill up with water because of several reasons. For example, fill valve problems, flapper valve issues, low water pressure, and others. Moreover, the toilet waterline or water pipe also created this problem.

Wrapping Up!

The Toilet tank needs to fill up with water is a common problem. Most of the time, this problem comes out because of a fill valve problem, low water pressure, worn-out flapper valve, and leakage problem. The plumbers found these problems several times. However, you will easily solve them after checking out the above article.

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