How to Fix a Slow Filling Toilet Tank – 5 Simple Solutions

Need to find out how to fix a slow filling toilet tank but not sure what the cause is?

Here are some common reasons why your toilet tank might be filling slowly and how you can fix the problem. We’ve compiled this list of tips to help you diagnose the issue and find a solution that works best for you. You’ll have your toilet back up and running in no time!

Check out these quick fixes before calling a plumber or replacing parts on your own!

First of all, we may need to find out how long should a toilet take to fill.

How long should it take to fill a toilet tank?

When your toilet tank is properly working, you should be able to flush the toilet once and have it refill between 1.5 to 3 minutes.

If a toilet tank takes longer than that, there’s probably an issue causing the slow fill rate. To determine which part of the system is at fault for the slow filling time, read on.

What to do when your toilet takes too long to fill – 5 Causes and Easy to Follow Solutions

Because many factors can affect the rate at which your toilet fills, it’s best to cover a few common causes before you dive in. Our list covers trouble-shooting tips for slow filling toilets including water flow problems, cranking and flushing issues, clogged drains, and other common fixes.

Here’s our how to fix a slow filling toilet tank step by step guide.

1. Water supply valve problem

A water supply valve (also known as the shut-off valve), is a little knob on the wall just behind the toilet. It regulates the amount of water that enters the toilet tank. When you turn it clockwise, less water flows into the tank. Conversely, if you turn it counter-clockwise, more water will go into the tank. A valve is essentially just an on/off switch. If the valve is not fully open, then water will be unable to fully flow into the tank. However, if there is debris clogging the valve, then even if the valve is fully opened, water will not be able to flow into the tank.

What to do when the water supply valve is not fully opening?

If you see some water trickling out of your toilet’s supply hose then it is likely that something is blocking the water supply. For example, a kink in the hose or an object caught in it. In such cases, you can try turning the shut-off valve on and off to unclog any debris stuck inside it.

Cleaning a blockage in the shut-off valve

If this doesn’t work then you will need to use a plumbing snake (or auger) to clean out the debris inside of it.

With the water supply off, you will have to remove the valve and use the auger to clear any debris inside. With the aid of some towels, you can turn the water on slightly to see if the flow has improved.

If there is still only a dribble, then there could be a blockage further down the pipeline, which will need more expert help from a plumber.

If you want to replace your water supply line it is quite simple to do. Follow this short video instructions:

2. Waterlogged float ball

A float ball regulates the amount of water that flows into the toilet tank. If the float ball is full of water, it will hamper the tank from filling. As a result, it can cause the tank to refill at too slow of a rate, or even stop it from filling altogether.

How will you know if the float ball is waterlogged?

Remove the toilet tank lid and check to see if the float ball is floating on top of the water or is submerged in the water.

If it is floating on top of the water then it is working fine, but if it is under the water then it is probably waterlogged and you may need to replace it with a new float ball.

How do you replace a float ball?

It is very easy to replace a float ball. It is as simple as pulling off the old float ball and attaching a new one.

3. Fill valve tube issues

What is a fill valve?

The fill valve is located inside the toilet tank and regulates the amount of water that goes into the bowl. When you flush your toilet, the fill valve opens and releases a pre-determined amount of water into the bowl to create a vacuum for waste to be flushed away.

What Causes it to Slow?

The fill valve is connected to a vertical tube-shaped mechanism and controls the amount of water in the toilet tank. Fill valves can clog, wear down, or even shift out of position.

When this happens, the fill valve will not be able to function properly, causing it to slowly fill the tank.

How can you tell if this is the issue?

You will know that your toilet’s fill valve is the problem when there is not a steady flow of water flowing through the valve. When you lift the tank’s lid, you will be able to see if the fill valve is functioning properly by watching the water flow into the tank. If there is an issue with your fill valve it will create a noticeable difference in water flow.

How do I prevent this from happening?

The best way to prevent these issues is to regularly check that the fill valve is working properly by lifting the toilet tank lid and checking to see if the water is flowing smoothly. If it is not flowing smoothly, then cleaning it may remove any blockages and improve its performance.

How do I clean the outside of a fill valve?

If you feel that your fill valve could be blocked then cleaning it may solve the problem.

If the exterior of the valve has mineral buildup, scrub it off with a vinegar-soaked toothbrush and then rinse with warm water.

How to clean the inside of a fill valve?

Turn the water supply line off. Remove the valve top and cover the opening with an inverted plastic cup. Hold the plastic cup over the open valve to prevent water from spraying up and then turn the water supply line back on. This will flush out any debris that may be inside the valve.

4. Trip assembly issues

What is a trip assembly?

The trip assembly includes the handle, the trip lever, the handle chain, and the flapper.

Its purpose is to regulate how quickly or slowly the water fills the tank. If it is not adjusted properly, then it will cause your toilet to refill at a slower rate.

How do I fix a trip assembly?

If you have a slow-to-fill toilet, then adjusting your trip assembly may help.

The chain should have the correct amount of tightness so that when the handle is fully pressed the chain is tight enough to raise the flapper. When the handle has fully released the chain should be loose enough to allow the flapper to fall back into place again.

How do you adjust the chain?

You can tighten the trip assembly chain by removing the chain link from the lever and then going down a link or two on the chain. Reattach the link to the lever and then flush to see if it is the correct tightness. If it is not right yet, repeat the process until the chain is adjusted to the right height.

5. Flapper valve issues

One of the easier things to notice is if the flapper valve is fitting snuggly over the valve seat. If the flapper valve is looking a little worse for wear, then you may want to replace it.

What is a flapper valve?

toilet flapper
Korky Toilet Flapper: Image from

The flapper valve is an essential part of the toilet system. This flap-like rubber disk allows for water to flow in and out of the toilet tank at a regulated pace. When the toilet handle is pressed, the trip handle pulls on the chain. This chain then raises the flapper valve, allowing water to flow through the hole into the toilet bowl. When the handle is released, gravity pulls down on the flapper valve causing it to cover and seal the hole, allowing water to fill up the tank again.

How often should you replace a flapper valve?

The flapper valve should be replaced every 3-5 years depending on use or if you notice that your toilet tank is having problems refilling.

How to check if a flapper valve needs replacing?

To check if your flapper valve is functioning properly, remove the tank lid and then put a few drops of food coloring in the tank. Allow these drops to sit for 15 minutes. If the coloring starts to become visible in the bowl then your flapper valve may not be properly sealing.

How do I replace my flapper valve?

To replace the flapper valve, follow these steps:

Turn off the water supply line and flush the toilet to empty all the water from the tank. Remove the old flapper by pulling it out of the tank. Insert the new flapper valve by pressing it firmly against the tank drain hole. It should fit tightly around the drain hole. Secure the chain of the trip assembly to the hook attached to the flapper. Replace the water supply and flush the toilet again a few times to test the new flapper valve.

Conclusion to How to Fix a Slow Filling Toilet Tank

By now you should have a few theories on what is causing your slow filling toilet tank and just need to test them out.

Water supply problems, a waterlogged float ball, fill valve tube issues, problems with the trip lever assembly, or even flapper valve issues. There could be several issues causing your slow-filling toilet tank.

If the problem still exists after trying out these steps then you may want to seek professional help such as that of a plumber, to fix the problem.

Seeking help from a professional may cost you, but it can save you money in the long run by fixing your toilet properly and preventing further damages. If left unfixed, this could lead to more expensive problems such as needing a new toilet or other components.

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