Why isn’t My Toilet Tank Filling Up?

Toilets are commonly used throughout the day in homes, offices, and industries. One of the common issues you might face is the toilet tank not filling up properly.  The toilet tank is meant to refill with water after each flush. And as per Toilet Heaven, the water level should be about half inches below the overflow tube and refilling should take around 10 seconds. But in instances when this does not happen, that means something inside the tank is at fault. 

In this article, we will talk about all the possible reasons why your tank isn’t filling and how you can fix this problem. When the toilet tank does not fill up after flushing, it may be due to the inappropriately closed shut-off valve, low water pressure, faulty fill tube, leaking flapper valve, the incorrect height of float ball, or fractured overflow tube.

check the shut-off valve when the toilet tank is not filling up

Reason # 1 Inappropriately Closed Shut-off Valve

The first thing to check for when the toilet’s tank isn’t filling is the shut-off valve. Your children might have mistakenly closed it. It is on the rear wall of the tank. Turn it counterclockwise, and see if it is fully open.

A push/pull valve is seen on some toilets. Push the valve to turn on the water supply to the toilet.

Reason # 2: Low Water Pressure

Sometimes the pressure is so low that it’s as if there is no water at all. This could be a water supply issue. It could also indicate that your water pump is not working properly, especially if this is happening to numerous residents in the same building.

Another cause might be a leakage in metallic pipes due to rusting. To confirm, you need to check whether the low water pressure is impacting only your toilet or other sanitary fixtures. If the problem is only linked to the toilet, then look for leakage in the supply line.

How to fix the low water pressure issue?

If you have a really tall building, the top levels may have lesser water pressure. This necessitates the services of a pump technician who can install a booster pump.

In case of pipe leakage, you will need to call a professional plumber to replace the pipe.

Reason # 3: Faulty Fill Valve

The fill valve is normally located on the left side of the toilet tank. It connects the toilet tank to the water supply pipe. After flushing, it is the component of the toilet that pushes water back into the tank. It is also connected to the refill tube and the ball float on the inside.

If the fill valve isn’t operating, it could be due to a blockage or because it is too old and worn out to function properly. Fill valves can also fail at any time.

How to fix/replace the Faulty Fill Valve?

A faulty valve can be repaired but since it is not costly, the common practice is that you should replace the fill valve with a new one.

To replace the faulty fill valve, follow these steps.

  1. Firstly, you need to cut off the supply to the toilet. Turn off the shut-off valve.
  2. Take off the toilet tank’s lid.
  3. Flush the toilet by holding the lever down so that no water remains in the tank.
  4. Take out the lock nut by turning it counterclockwise.
  5. Then, disconnect the refill clip from the overflow tube.
  6. Now, you can remove the fill valve, so take it out. Clean the area around it.
  7. Adjust the fill valve’s height based on the size of the tank. For that, hold the top part and turn the bottom part counterclockwise until the desired height is attained. Fill valve caps should have a height of at least three inches above the overflow tube.
  8. Insert the fill valve and tighten its nut.
  9. Reconnect the overflow tube to the refill tube.
  10. Turn on the supply and the tank would start filling.

Reason # 4: Leaking Flapper Valve

Sometimes the toilet flapper is to blame if your toilet isn’t filling but the water is still running. For flushing, a toilet flapper acts like a rubber seal at the bottom of the toilet tank, opening to let flush water into the bowl and closing to keep water in the tank until the next flush.

flapper valve replaced
Image from Cathy Pearce

How to fix/replace the leaking flapper valve?

A leaking flapper valve cannot be fixed, so the best idea is to replace the leaking flapper valve. To replace the flapper, follow these steps.

  1. Firstly, turn off the shut-off valve. This cuts off the supply to the toilet.
  2. Remove the tank’s lid.
  3. Flush the tank by pressing the button or holding the lever. Make sure all of the water goes in the bowl and the tank becomes empty.
  4. Locate the flapper valve. It is in the bottom center.
  5. Before removing it, first, disconnect the lift chain of the flapper.
  6. Lift the flapper out of the overflow tube by removing the pegs holding it in place.
  7. Clean the area and install a new flapper valve. Reconnect the pegs and re-hook the lift chain.
  8. Turn on the water supply and place the lid back.

Reason # 5: Incorrectly Positioned Float Ball

The float ball is the most prevalent reason for the problem of the toilet tank not filling with water after flushing. In the tank, the float ball floats on the top. It is further attached to a float arm that regulates the amount of water entering the tank. So, once the water reaches the designated height, the float ball blocks the entrance of the water by moving the float arm.

black float ball in the toilet tank

How to position the ball float?

Occasionally, the float ball requires a little tweaking over time. So, the first thing you can try to correct the float ball position is bending the float arm slightly upward, so that the ball goes higher and stops the entry of water much later. Most of the time this fix can help out things.

If this thing doesn’t work, you may need to replace the float ball. Since the hollow interior is the main reason for floating float ball. So, when the float ball becomes old, it acquires fractures or holes that allow water into it. The float ball, which is no longer hollow, gets filled with water and doesn’t float very well.

How to replace the fractured Float Ball?

It is easy enough to replace a soggy float ball with a new one since it is a fairly inexpensive fix. Keep in mind these steps while replacing the fractured float ball.

  1. Turn off the shut-off valve. Open the tank’s lid.
  2. Make the tank empty by holding the lever down.
  3. In the old toilets, the ball floats are easy to remove. You just need to unscrew the ball float from the rod it is attached.
  4. Once the float ball is removed, screw a new float in place of it.
  5. Turn on the shut-off valve.

Some modern toilets that have an integrated float will need a more complex technique to remove. In that case, first, you will need to remove the nut that secures the valve to the tank’s bottom. Then, you will need to disconnect another small water hose inside the tank designated for the float ball.

Reason # 6: Fractured Overflow Tube

Another thing that can contribute to infilling of the tank is a fractured overflow tube.  Located in the center of the tank, the toilet overflow tube directs excess water from the tank to the bowl to prevent it from overflowing.

It is very uncommon to happen, but occasionally, the overflow tube can split and leak water into the toilet bowl. It can be replaced in a similar manner as we followed for the fill valve. They are located side by side.

In short, when your toilet tank is not filling properly with water, there are a variety of possible reasons for this to occur. First, you can try to replace the components in the tank by following our steps. However, some problems are beyond your fixation. If you suspect that the problem is not related to the toilet only, it may be in the piping system. Then, consult a professional as soon as possible. Otherwise, you are risking potential damage to the piping system.

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