How To Fix A Slow Filling Toilet Tank like a Pro

You are here, which means your Toilet tank is not filling properly. So don’t worry; you are landing in the right place.

You can get rid of all this if you follow some simple and easy tips, all you need two things to fix a slow filling toilet one is primary ideas, and the second one is time.

It might be a universal puzzle these dates. A homeowner has a big headache to get a plumber; it is going to a big process; again, spend some bucks for basic requirements.

The main reason why the toilet tank is not filling up is a possible problem with either the recharge valve or the flush valve. There are few reasons behind your toilet takes too long to fill, like water pressure, floating valve.

The first thing should know why the toilet tank is not filling; then, I’ll give a valuable step-by-step guide on how to fix a slow filling toilet tank within the next 10 mins.

I guarantee you can fix it quickly if you know the reason for not filling the water. If you would prefer to grasp all this, you have to stay with us for the next 10 minutes.

Table of Contents

Why is my toilet tank not filling up with water after flush?

There are a few reasons for your toilet tank not filling at all. Maybe the problem with either the flush flap or the refill flap is the major cause. But again, another few reasons are water pressure, water shut off the line. 

Before jump into causes, I want you to know the toilet flush mechanism that may big help to you.

A toilet tank contains the main three parts, and one part is a flush button or lever that does not cause fill up.

1. Fill Valve :

The fill valve or refill valve is one that connects with the water supply tank. This one is responsible for filling the tank after the flush.

The fill valve also connects with the refill tube and the toilet float. Toilet Float may be ballon shape in older one and cup shape in the newer one.

Mechanism of Fill valve:

  • After a flush, water release for the cleaning purpose next to the float moves to the toilet tank’s bottom.
  • Then water filling the tank.
  • The float moving up until the tank is full.
  • And this refill tube sends water down to the bowl through an overflow tube to prevent gases.
toilet tank not filling

2. Now come to the Flush valve/flapper:

The flapper is a rubber seal container set into the hole or drainage line directed into the bowl.

The flush valve connects to the flush handle through a chain. The chain should have 1/2 inch slack.


  • After each flush, the flapper’s chain lift and the flapper open and allow the water to go in the bowl through the rim jet.

3. Come to 3rd one Overflow tube:

A large tube present in the middle of the toilet tank. It is The main Channel where excess water run and prevent overflowing. But if something wrong with the overflow tube, you may suffer from not filling the toilet tank.

Check thoroughly one by one for the diagnosis.

There are a couple of factors present for the toilet tank not filling up.

i. only the Toilet tank not refilling after a flush or Slow filling toilet tank.

ii. Toilet tank not filling with enough water

iii. Toilet tank not filling but water running

Which one is yours?

I divided the causes according to these factors that are easy to understand.

What cause for a Slow Filling Toilet Tank

i. Only problem with the toilet tank not filling up after flushing Or a slow filling toilet tank

a. When you see only the tank does not fill, then check the refill valve. A fill valve defect can be the cause. Thus the toilet tank won’t fill.

b. Also, if some debris is present in the refill valve, water does not come enough to fill the tank or result as a slow filling toilet tank.

c. Check also the water supply tank. Older water supply tanks present various plaques and debris in them. Thus insufficient water supply may be the problem of the slow filling toilet.

How to fix this? I discuss it in the “how to fix” section.

ii. 2nd issue toilet tank not filling with enough water:

If you read the toilet part, I told you that the floating ball is responsible for the water level.

Check the floating bowl; if the floating bowl is too low, then causing the tank not filling enough water.

iii. 3rd issue is the toilet tank not filling but water running:

There are three reasons for this. 

No.1 Check flush valve:

One of the enormous probabilities is a defective flush valve. If the flush valve or flapper is damaged, then the tank’s water is leaking and starts to run.

In this case, all this time before the water fills up, all the water goes out.

No.2 Float:

If you can’t find any problem with the flush valve, then check the refill valve connected with the float. If the float level too high, then water will overflow in the bowl.

Just adjust float level and wait for some time to see what will happen. Again the same situation comes, next look for the overflow tube.

No.3 Overflow tube:

Although not often overflow tube can crack, they continuously send water into the bowl and do not fill the tank.

After watching so many things, if none of them are faulty, then there are the last two options.

I. Shut off valve, II. Water pressure:

Open the shut-off valve in the right way. The close shut-off valve may not release the water supply for the tank.

II. Water pressure: it will be the last checking point. When your fill valve is in good condition and the flush valve also in a good position, check your water pressure.

Low Water pressure is the primary cause of not filling with enough water.

This time you can’t do this. You call your water supplier and talk to them.

Other problems have hacks that can quickly solve in 5 minutes.

Now I think you know the reason why your toilet tank not filling up after flushing and takes too long to fill. According to your cause look at how to fix a slow filling toilet tank.

How To Fix A Slow Filling Toilet Tank Not Filling Up After Flushing

No. 1 After confirming the defective refill valve, simply replace it.

The toilet refill valve controls the amount of water present in the tank, so it is good to replace or check every five years.

How to replace it? I’ll tell you to step by step follow my guide.

  • Before going to replace it -Check any debris present or not. Thus you can start by turning the water supply line off into the tank.
  • Completely flush the toilet and make sure no water remains in the tank.
  • Place one hand at the bottom of the refill tube, place another on the cap, and rotate clockwise to lift it.
  • Watch the tube, any debris present or not.
  • To avoid water dash, secure the refill cup, and open the water supply so that water pressure could remove debris easily.
  • Inspect debris comes out and place the cup in the fill tube where you lift it.
  • Then verify thoroughly.
  • Wait for 10 minutes. The water in the efficient tank is usually filling; If not, the refill valve will replace.

Now how to replace a refill valve for slow filling toilet tank?

  • At first, switch off the water line to the bathroom.
  • Complete flush down for water drainage and remove the tank lid.
  • Disconnect the water supply, which connects to the refill valve.
  • Replace the refill valve from the old to the new one. Make sure to follow their guide.
  • Another point is to match and buy the exact size of the refill.
  • Before place, the refill valve cleans the enclosing area.
  • After secure the valve, attached everything as same as before look.
  • Connect refill tube to the overflow tube.
  • Join the water supply line and open the line.
  • Then check the filling amount.
  • The whole process takes only 45 mins to 1 hr or less.

Then you go.

2nd issue How to fix toilet tank not filling up with enough water:

  • This is caused by adjusting the floating ball in an old toilet and the new toilet instead of a floating ball use cup.
  • Just do one thing adjust the height by increasing the floating ball.
  • The floats are of different styles. 
  • In the older bathroom, the float hangs along a metal or plastic rod at the end of a wire. Generally, there are bolts attached to the water valve.
  • The level at which the water valve turns off would change with the screw.
  • You could be bent on the metal’s support if there’s no squeeze or it’s already at its limit, but remove it from the valve and possibly break the fill valve. 
  • In new toilets, the float is present around the filling valve’s neck, which goes upward. The float normally has a spring strap attached to a metal rod that links with the shut-off of the valve. Squeeze the spring clip up or down the metal rod to move the float. It is then filling the level. 

Hope you understand the process, move to another one.

3rd Issue How To Fix Toilet Tank Not Filling But Water Running:

No.1 Check the flush valve & How to replace flush valve :-

  • If the flush valve is a defective one, then simply replace it with a new one.
  • Turn of the shut off valve right behind the toilet bowl.
  • Flush the toilet completely and make sure remove the excess water
  • Take aside the toilet cover/lid then detach the lift chain from the flapper.
  • Then detach the flapper hands, which are bond to the overflow tube.
  • After unhooked all flapper clean the area and place the new one.
  • Hook the uplift chain and attach the over flow tube.
  • Connect the water supply and watch for the toilet tank filling without running water.
  • Cover with the lift.

How to replace the overflow tube:

  • Replacing the overflow tube is extremely easy task to do. 
  • Simply drag out the old valve and place it right there.
  • Remember in your mind that the new overflow tube will be the right size.

 How to Fix the water pressure :

Now am going tell you how to check water pressure. Very first things know about water pressure is check all other fixtures, if water pressure only problem then your all fixtures suffer for low water supply.

Are you noticing?

If this occurs in toilet then thoroughly check the water line. Do one thing here, blow air through the supply line.

Call a trained plumber to solve it.

Check the video for easily understand on how to fox a slow filling toilet

Conclusion on toilet tank not filling and how to fix a slow filling toilet

After explaining so many reasons unless you understand; And if you think it’s a risk to do it, you should call a good plumber and get rid of all these toilet problems.

Because the toilet is a place where we have to use every day, a slow filling toilet can ruin the beauty of your bathroom as well as make it unhygienic.

To avoid this type of messy problem always choose a best toilet. and clean regularly with DIY homemade toilet deodorizer.

Let our little tips come in handy, and you will be free from the cost of a plumber.

FAQs on Slow Filling Toilet Tank

How Long A Toilet Should Take To Fill?

It usually takes three minutes of average water pressure supply a toilet tank takes to fill.

Why is my toilet tank filling slowly?

A slow-filling toilet tank can be caused by various factors, including a blocked fill valve, a faulty float mechanism, a partially closed water supply valve, or sediment buildup in the water supply line.

What could be causing a slow fill in my toilet tank?

Several potential causes can contribute to a slow-fill issue in a toilet tank, such as a malfunctioning fill valve, a low water pressure supply, a clogged water supply line, or a misaligned float mechanism.

How can I fix a slow-filling toilet tank?

To address a slow-fill problem, you can try several solutions. These include adjusting the float mechanism, cleaning or replacing the fill valve, ensuring the water supply valve is fully open, checking for any blockages in the supply line, or increasing the water pressure if it’s too low.

Are there any DIY solutions for a slow-filling toilet tank?

Yes, there are some DIY solutions you can try. These include cleaning the fill valve by removing any debris or sediment, adjusting the float mechanism to the appropriate water level, and ensuring there are no obstructions in the water supply line.

However, if you are uncertain or unable to resolve the issue, it’s advisable to seek professional assistance.

Is a slow-filling toilet tank a sign of a larger plumbing issue?

In some cases, a slow-filling toilet tank may indicate an underlying plumbing issue. It could be a symptom of a clogged or damaged water supply line, a malfunctioning valve, or a problem with the overall water pressure in your home. If the problem persists or is accompanied by other plumbing issues, it is recommended to consult a professional plumber for a thorough inspection.

Can a faulty fill valve cause a slow fill in the toilet tank?

Yes, a faulty or malfunctioning fill valve can be a common cause of a slow-fill issue in the toilet tank. The fill valve controls the water flow into the tank, and if it is not functioning properly, it can restrict or impede the filling process.

What are some common reasons for a blocked fill valve in a toilet tank?

A fill valve can become blocked or obstructed due to sediment buildup or debris in the water supply. Over time, minerals and particles can accumulate, hindering the flow of water and causing a slow-fill problem.

Should I replace the fill valve if it’s causing the slow fill issue?

If cleaning the fill valve doesn’t resolve the slow-fill problem, or if the valve is old or significantly damaged, it may be best to replace it. A new fill valve can ensure proper water flow and a more efficient filling process.

When should I seek professional help for a slow-filling toilet tank?

If DIY solutions do not resolve the slow-fill issue, or if you are unsure about performing any repairs yourself, it is recommended to seek professional assistance.

Additionally, if the slow-fill problem is persistent or accompanied by other plumbing issues, a professional plumber can accurately diagnose and address the underlying causes.

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