3 Reasons Why Your Toilet Is Filling Slowly

3 Reasons Why Your Toilet Is Slow to Fill blog banner

Is your toilet filling slowly every time you flush? If so, you're not alone. A slow-filling toilet is a common problem for homeowners.

There are a few different reasons why this issue might happen. Thankfully, identifying the problem brings you one step closer to getting your toilet running perfectly once again.

We'll explain three common causes of a slow-filling toilet, how to troubleshoot the problem, and the steps you can take to fix it.

Three Possible Reasons for a Slow-Filling Toilet

In most homes, the toilet tank takes about one minute to refill. If the refill takes a lot longer than that, you may have an issue.

Here are three common reasons your toilet is filling slowly:

1. Water Supply Valve Problem

The water supply valve is a knob that sticks out from the wall just beneath your toilet tank. It controls water flow. When the valve is closed or broken, it may not deliver water at the right speed or volume. The water line this valve controls is also susceptible to clogs, which can impact how quickly your tank fills.

Troubleshooting tip: Check the valve to make sure it's completely open. If the valve is open and still not filling the tank, contact a licensed plumber to check the valve for debris buildup.

2. Waterlogged Float Ball

A float ball is a device that sits on top of the water in your toilet tank and sets the tank fill level. If the float ball fills with water, it will sink low in the tank and stop water flow too early.

Troubleshooting tip: Remove the toilet tank lid and check the water level. If it's only partially full or the ball is not floating near the top of the tank, you may have a waterlogged float ball. The good news is that replacing the float ball is straightforward. It's as easy as pulling the old one off the float arm and putting the new one in place.

It's worth noting that a float ball is old toilet technology. If this mechanism fails, consider updating your toilet's inner components.

3. Fill Valve Tube Issues

A fill valve controls the water level in the tank. Over time, this valve can wear down, clog, or fall out of alignment. All of these issues can lead to your toilet filling slowly.

Troubleshooting tip: If you've determined the problem is not the water supply valve or a waterlogged float ball, it's time to take a closer look at the fill valve. Inspect the valve for wear and tear or incorrect positioning inside the tank. It should typically be mounted on the left side of the tank with a tailpiece extending through the bottom, where it attaches to the supply tube and shut-off valve.

Slow Filling Toilet FAQ

How do I fix a slow-filling toilet?

Because there are multiple reasons behind a toilet filling slowly, there are multiple potential fixes. Here are a few different solutions that can resolve the issue:

1. Open the water supply valve

The first thing to check is the water supply valve. Fully opening a partially closed valve will solve your issue in a single step.

2. Adjust the fill valve

The fill valve in your toilet can fall out of place over time. When the valve isn't correctly aligned, your toilet will fill slowly. Follow these steps to adjust the fill valve:

  1. Remove the tank lid and find the fill valve — it's usually on the left side of the tank.
  2. Securely and evenly attach the fill valve to its tube.

    a. For older toilets, loosen the adjustment screw and raise the fill valve to let more water into the tank.

    b. For newer toilets, turn the fill valve adjustment knob by hand to allow more water into the tank.

    c. For all toilets, ensure the water level is about an inch below the top of the overflow tube.

  3. Flush the toilet and see if the tank fills properly.

3. Clean the fill valve

The gunk inside of a dirty fill valve decreases the rate of water flow, resulting in a slowly filling toilet. Notice mineral buildup or gunk on the valve? Then you need to clean it by following these steps:

  1. Twist the shut-off valve closed and remove the tank lid.
  2. Remove the screws on top of the fill valve, then remove the fill cap.
  3. Slowly turn on the water supply and cup your hand over the valve to avoid getting sprayed.
  4. Let the water flow freely through the valve to flush out debris and buildup.
  5. Turn the water supply off after a few seconds.
  6. Flip the fill cap and find the washer. Remove the washer with a screwdriver and gently scrub away any mineral buildup. If you notice cracks, replace the fill valve.
  7. Put the valve back in place, secure it with the screws, and turn the water on to see if you've fixed the problem.

4. Fix or replace a waterlogged float ball

A waterlogged float ball will prevent your toilet from filling to the proper level. Here's how to fix and replace the float ball in your toilet tank:

  1. Check whether the float arm attached to the float ball is fixed too low in the tank. If that's the case, bend the arm slightly upward so the ball rises higher in the tank, allowing more water flow.
  2. If this doesn't work and you still think the float ball is the issue, you may need to install a replacement float ball or contact your local plumber about upgrading to a newer style mechanism.

5. Fix a valve tube problem

To fix a clogged valve tube, you must clear out the debris. Here's how:

  1. Shut off the water supply to the toilet.
  2. Remove the hardware from the valve using the appropriate tools. Usually, this requires a screwdriver and a wrench.
  3. Clean out the tube using a slim wire or bottle brush.
  4. Open and shut the water supply valve a few times to flush away any remaining residue and clear all of the clogs.
  5. Replace the hardware and the tube and check to see if the toilet fills properly after flushing.

Replace the tube if it is broken, torn, or otherwise damaged.

If a broken pipe or pipe buildup is causing your toilet to fill slowly, call a plumber immediately.

Choose Mr. Rooter® Plumbing for Toilet Repair and Replacement Services

If you don't want to attempt a DIY plumbing job or prefer a reliable, quality solution from a professional, Mr. Rooter® Plumbing is here to help. The licensed plumbers at your local Mr. Rooter Plumbing can provide the toilet repair and replacement services you need. Call today or request an estimate online to get started.