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Toilet Tank Not Filling Up? Here’s How To Fix A Slow Filling Toilet!

A slow filling toilet tank can be a sign of bigger issues. If you don’t deal with it quickly, you could find yourself with a toilet tank that won’t fill with water at all. Here is how you fix a toilet tank that is not filling with water. Best of all, you can do all of these without calling a plumber.

Toilet Tank Not Filling Up

Why is My Toilet Tank Not Filling with Water?

The reason your tank isn’t filling with water will be one of several reasons. The first one is that the flapper isn’t properly closing. This will leave you with a running toilet because all the water is coming into the tank and draining right back down into the toilet bowl.

The next reason is that you have debris issues clogging the main water line coming into the tank. This can cause a slow filling tank or tank not having any water come through it all. This means that the line and/or the fill valve will need to be flushed.

Don’t worry; it’s easier than it sounds.

The third reason Is that the toilet float arm is stuck or broken and will need to be adjusted or replaced.

Finally, the overflow tube may be cracked, and water is going into the toilet bowl instead of filling up the tank.

Toilet Tank Filling Up Slowly

How To Fix A Toilet Not Filling With Water

Step 1: Take off the toilet tank lid

The first thing you’ll do is remove the lid of the toilet tank. Place it on a flat surface out of the way. Toilet tank lids can break if pressure is put on the wrong spot, and they are expensive to replace.


Step 2: Inspect the toilet tank

Check the tank to make sure that there is water flowing into the tank. Next, in the following order, check these four items.


1. The toilet flapper is closing.

The toilet flapper should be closing and making a tight seal. If your toilet lift chain is too long, it can get in the way of your flapper closing.  Adjust the lift chain by shortening it so that there is only a little bit of chain when the flapper is closed. The lift chain should be pulled straight up when the flush handle is pressed.

Or, if your flapper is very old, the flapper may be worn out and may not be sealing properly. This can happen when debris gets in between the flapper and the flush valve for the water to go through.

Without the flapper forming a tight seal, the water supply will be minimal. That’s because the water will leak through to the toilet bowl, and your tank will not fill up. This will lead to a weak flushing toilet or no flush at all. A worn-out flapper is a common toilet repair and is easy to fix, and replacing it will have your toilet fill properly in little time.

loose flapper causes toilet fill slowly

Toilet flapper can wear out over time or fill with debris causing your tank not to fill up.

2. Inspect the overflow tube

The overflow tube can crack, and it will continuously send the flow of water into the toilet bowl. This can be a cause of water constantly running and your tank not filling up.

If this happens, you will need to replace the overflow tube. It’s a very straightforward repair as long as you buy the right tube size.


3. Inspect the float

Make sure that the float is coming all the way up to the top. These can have a float ball attached to the float arm or a float cup on the fill valve.

Gently grab the toilet fill valve and slide the float cup up to see if that is the issue. If water starts to rise and push the float back to its normal resting position, you may have fixed it right then and there. Give the toilet handle another flush to see if this corrects the issue. The float should come up to the top.

If you have a ball float, it’s likely you have an older toilet, and things could be breaking down. Check the float arm and float ball to make sure they are set to the proper level. These arms can be bent and cause the float ball to sit too long, causing your tank not to fill up.

If the float valve is set too low or is stuck, the tank isn’t filling to its proper level, and it will need to be adjusted. Use a flat head screwdriver to adjust the level of the ball float in the tank.

The water level needs to be about half an inch below the overflow refill tube; you will want it to reach that level to ensure a strong flushing toilet. Filling the tank shouldn’t take any more than 10 to 15 seconds to fill, depending on the water pressure you have in the house.


4. Check the trip assembly

The trip assembly is the part that comes from the toilet handle into the tank. If the lever gets bent or worn out, it could be causing issues with other parts of the tank and should be replaced.


5. Next, inspect the fill valve

Look at the valve to see if the water is coming through it. If there is no water coming into the toilet tank, you will need to inspect it for a blockage. Your valve may have debris build-up, and simply cleaning it off can do the trick.

If neither of these is the issue, it could be that there is debris in the supply line coming to the toilet or in the valve.

Related: Toilet Keeps Running? Here’s how to fix it!


Step 3: Turn off the water supply line

Before you go any further, you should turn off the water supply of the toilet. The water supply valve will be found at the base of the toilet by the floor or going into the wall. Next, you will want to flush the toilet to remove any water from the tank.


Step 4: Flush out the fill valve to remove any debris

If water is slowly coming into the tank or not coming in at all, it’s likely that the valve is broken or clogged.

Check first to see if it is clogged and remove any debris from inside the valve by doing the following:

1. Remove the cap of the fill valve

To do this, grab the shaft of the valve with one hand while you turn the cap of the valve with the other counterclockwise. This will remove the cap and the lever from the rest of the valve.

2. Inspect the seal

Inspect the seal inside the cap to make sure that it is clean of debris and not worn out.

3. Cover valve with an upside-down cup

Next, get a plastic cup upside down over the top of the shaft of the valve.

4. Turn water on to flush it out

With the cup upside down and ready to catch any water, turn the water back on and allow the water to run for 30 seconds so that any debris can be pushed out. Once the water is flowing again, fully turn the water off.

If there was no water or very little water coming through the top of the fill valve, move on to the next step, as your pipe coming into the toilet may be clogged.

5. Replace the fill valve cap

Once that is done, put the toilet cap lid back on by giving it a turn clockwise.

6. Turn the water back on

Turn the water back on and see if the tank fills back up. If it is filling up again, you have fixed the problem.

Step 5: Unclog the main supply line into the toilet tank

mainline into the toilet tank

If removing the debris from the fill valve didn’t work, or if there was minimal water pressure coming up through it, it’s likely that the mainline into the tank is clogged. Here is what you need to do to unclog the line coming into your toilet.

  1. Make sure the water is still off.
  2. Pace a large bowl underneath the shut-off valve to catch the water.
  3. Use a wrench to loosen the lock nut from the mainline to the shut-off valve.
  4. Inspect the line to see if there are any blockages. Use a pipe cleaner or this device to try and remove any buildup that’s happened in the pipe.
  5. Reattach the pipe to the shut-off valve and snug it with a wrench.
  6. Turn the tank back on and make sure the reattached hose is not leaking or dripping water.
  7. See if the water is coming into the tank at a good water pressure.
  8. Flush the toilet again and see if the water pressure has increased and water is filling the tank.

If this didn’t fix the issue, it’s likely that there is a problem with your fill valve and needs to be replaced.

Related: Read this if you have low hot water pressure.


How to Replace a Toilet Fill Valve

Replace Toilet Fill Valve If you’ve adjusted the fill valve and nothing seems to be working, you may need to replace it. Replacing the fill valve can be done using these simple steps.

  1. Turn off water to the toilet tank at the mainline shut-off valve (look underneath the tank on the floor or coming out of the wall for the knob).
  2. Place a bowl underneath the mainline and the tank to catch any water.
  3. Flush the toilet to remove any water from the tank.
  4. Disconnect the main water supply line coming into the toilet from the shut-off valve.
  5. Remove the lock nut underneath the base of the tank by turning it counterclockwise.
  6. Detach the line from the cap of the fill valve from the overflow tube.
  7. Remove the fill valve.
  8. Drain the remaining water from the tank.
  9. Clean the area of the hole where the new fill valve will be going to ensure a tight seal.
  10. Insert the new fill valve into the tank and tighten the nut underneath with your hand at first and then snug it with a pair of pliers
  11. Attach the fill tube from the fill valve to the overflow tube
  12. Reattach the waterline and snug it with pliers or a wrench
  13. Gently turn on the shut-off valve to restore water flow.
  14. Watch the water fill up the tank and inspect for any leaks if any leaking water snug the parts a little more.
  15. Adjust the fill valve float to the right water level and flush the toilet.
  16. Ensure the tank is filling up to the water level indicated by the manufacturer.
  17. Replace the lid of the tank.
  18. Make sure the toilet bowl is filling up at its normal level.

There you go, you have replaced the toilet fill valve, and your toilet should be filling up again like it is brand new. 

Final thoughts on toilet tank not filling with water

slow filling toilet

Your tank can easily be fixed using the methods above. It’s important for your toilet to flush properly and these fixes require very few tools (most you can do with a flat head screwdriver).

If you have tried these and nothing seems to work. Or you still can’t get water coming into your tank; it’s possible that there is an issue before the water is reaching the shut-off valve to the toilet. If this is the case, you will need to contact a professional plumber to help you with this. Use the link below to find a plumber in your area.

Click Here to Find a Local Plumber

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