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How To Fix A Slow Filling Toilet Tank Without Calling A Plumber

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

If you’ve ever had a problem with your toilet that you couldn’t fix with a plunger, you’re probably familiar with the sinking realization that you’ll need to call a plumber.

How To Fix A Slow Filling Toilet Tank Without Calling A Plumber

Hiring a plumber to take a look at and fix your toilet costs a lot of money, so understandably, it’s not something that many of us relish. 

While, in some cases, you may encounter toilet malfunctions that simply can’t be fixed without professional assistance, there are some common problems that you might not realize you can resolve by yourself.

One such issue is a slow-filling toilet tank. 

A toilet tank that takes too long to fill up can be a major inconvenience.

If you’re sharing a bathroom, for example, it can be very annoying to have to wait five minutes or longer for the tank to be ready to flush after the last person used it. 

If your toilet tank is filling up slowly and causing you stress, don’t worry.

We’re going to walk you through the process of fixing this issue yourself without calling a plumber. 

Reasons For Slow-Filling Toilet Tanks 

Before you can start trying to fix your slow-filling toilet tank, you’ll need to do some troubleshooting.

This is usually done by a process of elimination, trying one thing at a time to see if anything solves the issue. 

Luckily, there are some common reasons why your toilet tank might start taking longer to fill up, so you don’t have to do too much guesswork.

In the majority of cases, slow-filling toilets are caused by one of the following:

Clogged Tubes 

By far one of the most common causes of a toilet tank that fills too slowly is clogging of the tubes inside the valve.

Thankfully, this is also one of the easiest problems to fix. 

In most cases, tubes in toilet valves get clogged because of a simple build-up of debris. 

All you need to do to remove the blockage is shut off the valve so that water stops flowing into the tank, remove the hardware attaching the valve to the tank, and insert either a small cleaning brush or a length of wire into the tube to dislodge the clog. 

To make sure that you have fully unclogged the valve, you should turn the valve back on and turn it off a few times.

Once you’re sure that the water is flowing as it should, you can go ahead and screw the hardware back into place.

The next time you flush the toilet, the tank should fill up more quickly. 

Partially-Closed Valves 

While you’re checking to see if the valve in your toilet tank is clogged, you should also make sure that it’s fully open.

This sounds like an obvious thing, but sometimes, tank valves can partially close, preventing water from flowing freely into the tank. 

If you notice that the valve inside your toilet tank isn’t open all the way, simply open it back up and try flushing the toilet again.

Hopefully, this should allow the tank to fill up at the correct rate compared to the slow flow of water you noticed before. 

Low Water Pressure 

If the water pressure in your plumbing is too low, water will not be able to flow through the pipes and into your toilet tank as quickly.

This can result in you waiting around for a long time before your toilet tank is full enough to flush. 

Therefore, if there doesn’t seem to be anything wrong with the valve in your toilet tank, it’s a good idea to check the water pressure to see whether this is at the root of the issue.

You can do this fairly easily if you use a well because all you need to do is turn the pressure up at the tank.

If this doesn’t work, but it still seems like the problem might be with your water tank, you may need to replace the tank altogether or, at the very least, replace the pump. 

Fixes For Slow-Filling Toilet Tanks 

How To Fix A Slow Filling Toilet Tank Without Calling A Plumber

We covered some of the easier fixes for slow-filling toilet tanks alongside the most common causes of this malfunction. 

However, there are some other relatively quick fixes that you can try at home instead of calling a plumber. These include: 

Readjust The Float Bail 

A float bail is a toilet component that floats on top of the water in your tank’s reservoir. 

This piece of equipment is what determines how much water flows into the tank because there is an ‘arm’ attached to it that physically blocks more water from entering the tank when it has reached a specified limit. 

Now, if your float bail is too low down in your toilet tank, this obviously stops enough water from getting into the tank.

In this case, you might be flushing your toilet and thinking that it’s still filling up slowly, when in fact, the float bail is set too low and is preventing water from coming up high enough. 

Luckily, there is a very easy fix to this problem. If you can locate the arm on your float bail, all you have to do is gently bend it upward.

You don’t need to adjust it too much – just a slight bend should be enough. 

If moving the arm doesn’t help to fix the water levels in your toilet tank, you may need to replace the float bail altogether, but this will still be much cheaper than calling a plumber to investigate the issue. 

Raise Or Lower The Fill Valve 

We mentioned earlier that your toilet tank’s fill valve (see also ‘Best Toilet Fill Valves Available Today‘) might be responsible for your toilet tank’s slow fill time. 

Your fill valve controls the flow of water from the source tank into your toilet’s reservoir, so it makes sense that if this isn’t working properly, your tank won’t be able to fill up as quickly as it should. 

In some toilets, the fill valves are connected to the arms of the float bail.

If this is the case with your toilet, you should remove the cap from your tank to locate the valve. 

Then, take a screwdriver (this will need to be flat-headed) and turn the adjustment screw clockwise.

This will raise the valve, causing more water to flow into the reservoir.

If you need to lower the flow of water again at any point in the process, you can simply turn the screw back in the other direction (anticlockwise).

Once you feel that you have adjusted the valve to the correct level, do a check by simply flushing the toilet.

If the problem is fixed, you should notice that your tank fills up more quickly. 

Correct The Trip Assembly 

The trip, also known as the trip handle, is linked to the handle that activates your flush.

If your plumbing isn’t the best, this handle can end up in the wrong position and become blocked.

If you put the lid on the trip before the rinse cycle is complete, the trip can get blocked as well. 

To see if the problem with your toilet tank is connected to the trip handle, you should remove the lid and look at how the trip has been assembled.

If it’s at all crooked, it’s very possible that this is the root of the issue. 

However, it’s not easy to repair a badly positioned, crooked, or blocked trip assembly, so the best course of action is to replace it entirely.

Again, this obviously isn’t ideal, but you can still do this for a more affordable price than hiring a plumber. 

Check Your Water Pressure 

At this point, if you’ve been making your way down this list, you should have checked all of the easily-fixable areas of your toilet’s tank that could be responsible for how slowly it is filling. 

If none of these fixes have worked, it’s likely that the problem is not with the tank itself but with your water supply.

Most of the time, this is down to low water pressure.

If you’ve noticed problems with any other appliances in your home that rely on a supply of water (your dishwasher or washing machine, for example) it’s even more likely that your plumbing and water pressure are to blame. 

To make sure that your water pressure or plumbing isn’t the cause of your slow-filling toilet tank, you should check each individual pipe leading to your toilet.

If any of the pipes appear to be old or damaged by corrosion, they should be replaced.

Leaks, of course, can cause the overall water pressure in your pipes to drop, so if you find a leaking pipe, you can bet that it’s at least part of the problem. 

Now, this in itself may require the assistance of a plumber, but if that’s the case, at least you can go into the process with the problem diagnosed rather than having the plumber do all of the investigative work from start to finish. 

Extra Tips For Fixing Slow-Filling Toilet Tanks 

How To Fix A Slow Filling Toilet Tank Without Calling A Plumber

Did you know that debris and sediment in your water supply can accumulate in your fill valve and cause your toilet tank to stop filling up efficiently? 

We’ve already discussed how to check your fill valve for clogs, but this process isn’t always as easy as it sounds, so for a more in-depth explanation of the process, read on!

To get rid of debris that may have accumulated in your fill valve and water supply, you should: 

  1. Turn off the fill valve so that no more water enters the tank after you flush it. 
  2. Lift up the float cup and take hold of the shaft (this will probably be gray). Hold the shaft firmly so that you don’t drop the cup or make the valve move. 
  3. Keeping your hand on the cap of the valve, take the thumb of your free hand and turn the lever counterclockwise to unlock the lid. Then, you can take off the lid and lever. 
  4. The first place you should check for sediment and debris is in the seal. This is a ring made of rubber with a pin sticking out of it. Also, take a look at the part of the valve that remains in the tank. 
  5. Hold the cup upside down over the valve hole, which should be exposed, and turn the water supply back on. You don’t have to do this for long – between 10 and 15 seconds should be enough. The water flow should dislodge any debris. 
  6. Put the top back onto the valve and ensure that the arm coming off the cap is positioned beside the tube. Push down while turning the top of the valve as well as the arm in a clockwise direction. 

Again, if trying to flush out the valve using the water supply doesn’t fix your problem, but you still think the valve is responsible, the next logical step is to purchase a replacement valve and see if this makes a difference. 

When To Call The Plumber 

If you have tried all of the different fixes for slow-filling toilet tanks, including our extra tips, it’s probably time to call in a professional. 

Sometimes, even problems that are generally fixable from home, like slow-filling toilet tanks, have more complicated underlying causes that are difficult to diagnose, let alone fix, without a plumber. 

While you may feel disappointed that you weren’t able to save time and money by fixing your slow-filling toilet yourself, remember that it’s always best to admit defeat and consult a professional than to keep trying to fix the problem with limited knowledge or experience.

This could result in further damage to your toilet, or even your plumbing, and end up costing you more than you would have had to spend in the first place. 

Frequently Asked Questions 

How Long Should A Toilet Tank Take To Fill? 

The answer to this question may be slightly different for different types of toilets, but on average, a toilet tank should not take longer than about 3 minutes to fill. 

If it’s taking significantly longer than this, or if the amount of water flowing into the toilet bowl doesn’t seem sufficient after this time, you may need to start investigating what is causing your tank to fill so slowly. 

Why Does My Toilet Run So Long After Flushing?

If you keep hearing water running for a long time after you’ve flushed the toilet (as in, longer than 3 minutes), it might be because you have the water level in your tank set too high.

Often, this is down to the float bail in your tank being positioned too high up. 

If the water level is set too high, residual water will continue to run into the flow tube.

Over time, this can cause a number of problems with your toilet, so it’s important to correct the issue right away.

Thankfully, this is easy to do simply by adjusting the height of the float bail, lowering it so that the maximum water level isn’t so high. 

How Long Should It Take A Toilet To Flush?

The amount of water (measured in gallons) that flows into the toilet bowl when the toilet is flushed varies from unit to unit.

For example, some economical flushes use just 1.8 gallons of water, and therefore, they don’t take as long to flush.

On the other hand, some flushes use more than 7 gallons. However, your toilet shouldn’t take more than 15 seconds to flush.

If it does, you may have an issue with the water level in your tank or a water pressure issue. 


Using the tips and tricks in this guide, you should be able to fix or at least diagnose the problem behind your slow-filling toilet tank without calling a plumber. 

Usually, if your toilet tank is filling too slowly, it’s down to the valve, the float bail, the trip handle, or your plumbing in general. 

If none of the fixes in this article work, please call a plumber so that your toilet doesn’t sustain any further damage.

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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