Reason Why The Toilet Tank Not Filling: How to fix the issue?

You may have come across the issue, the toilet tank filling slowly or the toilet tank not filling up accurately. A toilet is designed to refill in less than a minute. If your toilet tank is taking longer, it may indicate a problem.

Faulty valves, leaking flapper, cracked overflow tube, or low water pressure are common reasons for toilet tank filling slowly or the tank not filling up. A person with DIY skills can easily manage to fix it. However, it is better to hire an expert plumber to take care of your plumbing issues. 

In this article, we will list some of the reasons and appropriate solutions for why your toilet cistern is filling up.

Why is my Toilet Tank Not Filling Properly?

Without knowing the problem, you can’t fix the issue. Sometimes the component inside the tank may need replacement or get dislocated. Below are some of the reasons that cause low water in toilet bowls.

Adjust The Toilet Float 

Replacing The Toilet Flapper

When it comes to the toilet tank don’t fill correctly, the first thing to suspect is the float ball. Your toilet will either have a float ball or a float cup. Usually, old toilets were using float balls, while the modern toilets come with float cups. The float ball sits above water in the tank and is connected with a fill valve, and controls the valve opening and closing. When the float is set too low, the water in the tank will remain low. If the float cup is set too high, excess water will fill the tank and flow down to the toilet bowl through the overflow tube. 

Even after adjusting the float arm, the ball remains low; you should replace it in that case.

How To Adjust The Toilet Float

In order to adjust the toilet float bowl, follow these steps. 

  • Turn off the water supply; usually, the shut-off valve is located at the toilet’s back. 
  • Flush the toilet by holding the lever down to remove most of the water. 
  • Remove the toilet tank and place it in a safe place. 
  • Now check if you have a float ball or a float cup. 
  • If you have a float ball, use a screwdriver to adjust the float arm connecting the fill valve and the float ball. Turn the screw clockwise to adjust the float arm to adjust the water level. 
  • While adjusting, do not turn the screw too much at once. Keep turning, opening, and closing the water supply until the water level is about ½ inch below the overflow tube. 
  • After adjustment, put the toilet tank lid. 

Replacing The Fill Valve

The toilet tank fill valve is connected with the water supply line, refill tube, and toilet float. After every flush, the valve fills the tank with water.

After flushing, the toilet float cup moves to the tank’s bottom, thus opening the fill valve. As the water starts filling the tank, the float cup gradually moves until it reaches its capacity. The refill tube sent a small quantity of water to the bowl via an overflow tube to prevent sewer gases.

If unluckily, your toilet fill valve has a fault, the tank will not fill up with the water. Most often, it happens due to piling up of debris or the valve seals worn out. 

If you have a fairly new valve or have recently replaced the valve and suspect the debris is clogging the water flow, you can quickly fix it with DIY skills. 

How To Fix A Toilet Fill Valve

  • Turn off the water supply to the toilet. 
  • Flush the toilet.
  • Use your hand to remove the fill valve. 
  • Inspect the valve holes for any possible debris, gently remove all the debris. 
  • After removing the debris, put the fill valve cap back on. 

If you have a worn-out fill valve, you should replace them as soon as possible. 

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Replacing The Toilet Flapper

Replacing The Toilet Flapper

If the toilet is not filling, but water is continually running, there may be a problem with your toilet flapper. A toilet flapper is a seal placed at the bottom of the toilet tank that allows flush water to enter the bowl and after the flush holds the water for the next flush. 

The flapper is connected to the toilet handle using a lift chain. The chain should have a ½ inch slack, if the chain is too tight, it will unseat the flapper and your toilet tank not filling but water running continuously. 

Another problem associated with the lift chain is that it gets loosen. After flushing the chain, enter the flapper hole; therefore, the flapper will not seal properly, and the toilet tank keeps running. 

If the toilet flapper is just worn or prone to leaking, the best practice is replaced. 

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How To Replace The Toilet Flapper

  • Turn the water supply of the toilet tank. The valve is located behind the toilet. 
  • Now flush the toilet and hold the lever as much as you can. 
  • Unhook the lift chain from the handle arm. 
  • Remove the pegs connecting the flapper with the overflow tube. 
  • Clean the area to install the new toilet flapper.
  • Now hook the lift chain to the handle arm. 
  • Open the water supply to the toilet. 
  • Check the toilet tank is filling, and there are no leaks. 
  • Place the lid back on the toilet bowl.

Call a Professional Plumber

Even you are a DIY enthusiast but unable to detect why the toilet tank isn’t filling up. It’s time to seek help from a professional plumber in your area; the plumber will quickly fix the tank issue.

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