How to Adjust Water Level in a Toilet Bowl? – 7 Ways

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Paulk Webb


Freddie J. Hagopian

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how to adjust water level in a toilet bowl

The water level helps you determine if the toilet functions properly or not. The sight of a low water level in the toilet bowl means a weak flush. On the other hand, the high water level is a warning that overflowing can happen.

How to adjust water level in a toilet bowl? To have the right water level in your toilet, you have to put the fill valve at the ideal height. In some cases, you might need to replace them.

Furthermore, some factors can alter the water level in the toilet bowl, such as a faulty fill valve, blocked toilet vent, clogged trap or drain, and worn-out refill tube. Learn more about this matter by reading the whole article.

Ways to Adjust Water Level in a Toilet Bowl


The concern of having the right water level in the toilet bowl begins with toilet fill valve adjustment. In addition, the fill valve has a float that moves with the water level inside the tank. It’s responsible for letting the water out of the toilet float valve when you press the lever or button. This also refills the tank and covers the valve once it’s full.

There are different kinds of fill valves and the adjustment of each of them will be shown here. Even though they’re in various forms, you’ll need the same materials:

  • A screwdriver
  • Penetrating oil (some situations may need this)

After the given steps for each type of fill valve, you can check the water level in the bowl after flushing. When there’s too much water, you have to make some adjustments.

1. Brass piston ballcock

A piston ballcock is a fill valve with a floating ball connected to a horizontal brass rod. This rod lifts and lowers the piston from the ballcock’s body so the water is released or blocked.

Just so you know, this fill valve is not common nowadays and is not a part of modern toilet units. Some old toilets have this but it needs adjustments to continue to serve.

Steps to follow

  • Bend the float rod carefully if you need to increase the water level in the toilet tank. You have to bend it downwards if you intend to decrease the water level.
  • You have to observe how the water moves and the level should be a bit higher than the overflow tube. Continue working on the rod until you achieve the ideal water level.

2. Diaphragm ballcock – plastic version


Apart from the brass ballcock, there’s a plastic version. This one has a lever that moves a plastic button on top of a bonnet. Then, a pressing force goes against the plastic diaphragm to control the water flow. You’ll find it more convenient to adjust the toilet water level to its height because of the adjustment screw on top of it.

You may find this valve in some toilets but it’s the toilet tank with a ball. Newer toilet models usually have the float-cup style.

Steps to follow

  • You’ll find a plastic screw mechanism that is used to raise or lower the float.
  • If you need to raise the water level in the toilet bowl, slide up the rod. It lowers the actuating rod if the water level needs to decrease.
  • The water level should be an inch under the overflow tube and the critical level point of the fill valve. If you have this setting, it’s guaranteed that the water level in your toilet bowl is right.

3. Cylinder float

It’s the latest fill valve type and of course, it’s more efficient than the classic brass and plastic ball and rod. As the name suggests, there’s a cylindrical plastic float that goes up and down the body of this fill valve.

These movements control the water flow. It has a floating cup that is attached to the valve by a screw mechanism or metal spring clip. There’s also a thin, metal rod that controls the valve.

Since this is an improved fill valve, it’s easy to adjust the water level once you find the screw mechanism. This is the type of valve that you can find in new toilet models made by famous brands like Kohler and American Standard.

You’ll need to let the float slip through the actuating rod if you want to increase water pressure in the toilet. In terms of decreasing the water level, you have to turn the top head counterclockwise.

4. Pressure-assisted fill valve


This is also called a floatless fill valve. It doesn’t work with floating devices but with pressure instead. Moreover, it’s an underwater valve that can determine the water level through the existing pressure. When there’s a lot of water in the toilet bowl, you have to twist the screw found on the valve’s top counterclockwise.

5. Fluidmaster fill valve

There are various Fluidmaster fill valves but the adjustment is done in similar ways. A universal Fluidmaster toilet water fill valve is great for any toilet.

Steps to follow

As long as there are no issues with Fluidmaster valves, you can proceed to do these steps.

  • Start with flushing your toilet to confirm the water level.
  • When you need to increase the water level, you have to twist the screw counterclockwise. It will be clockwise to lower the water level.
  • Flush the toilet to see if your toilet has the right water level. If not, repeat the previous steps.

6. Fill valve adjustment on dual flush toilets

A dual flush toilet bowl has two buttons for two, different GPFs. The higher amount of water is intended for solid waste while the smaller one is for liquid waste. You may

Steps to follow:

  • Once you take off the tank’s lid, use the screwdriver to turn the screw clockwise to make the water level drop. Do it in the opposite direction if the water in the bowl needs to rise. Flush if the water level gets back to normal.
  • If working on the screw didn’t work out, shift your attention to the lock with two sides. It’s rail-mounted on the side and linked to the fill valve at the same time. Press the lock to raise the water level. Flush again so you would see if the water level is good.

Read more: Dual flush vs single flush toilet: comparisons.

7. Other options for adjusting the water level in a toilet bowl

Fill valve and flapper replacement

If you’ve done everything you could to achieve the correct water level, there’s a need to replace your fill valve and flapper. Apart from seeing that the water level is too high or low, you can also witness a phantom flush or toilet flushing by itself and continuous water flow. These are the signs that the flapper and fill valve are worn out.

The ball and rod are the parts that need to be replaced in the classic fill valve. Replacing the cylindrical type is easy as it has a universal fit. After replacement, you have to refer to the previous instructions so you can have the correct water level.

Inspection of plumbing pipes and vent

The water level issue in your toilet bowl is not always because of the parts inside the tank. It’s sometimes with blocked plumbing pipes and vents. If the pipes are clogged, the water from the toilet can’t pass through. Thus, you have to face water that is higher than the normal level. To get rid of the blockage in plumbing pipes, you’ll need a plunger and snake.

You have to ensure that the vent is clear so the air can pass through. Without air, the vent is blocked and unbalanced and it causes poor water flow in the plumbing system that is connected to your toilet. The signs that the vent is blocked are gurgles and splutters when you flush the toilet.

In clearing the vent, get a ladder and garden hose before climbing your roof. To prevent incorrect water levels in your toilet, cover the vent to prevent dirt, debris, and other things from getting inside it.



How much water should be in toilet bowl?

The ideal amount of water in the toilet bowl varies as it depends on the toilet style. Generally, the water level should be over the P-trap drain or outlet to create a seal. It’s a vital part of creating suction for proper flushing. Additionally, it blocks bad odors from getting into your bathroom.

Why is the water level in my toilet bowl low?

When the water level is too low in your toilet bowl, there are several reasons like a faulty fill valve, damaged fill tube, cracks on the bowl, and blocked vent.

What determines the water level in a toilet bowl?

The water level in a toilet bowl is determined by the outlet height of the internal P-trap. That’s the reason why there are high water levels when there are clogged drain pipes.

Words to Ponder

Firstly, you have to check your fill valve on how to adjust water level in a toilet bowl. You’ve known different ways of adjustment as it depends on the type of fill valve that you have in your toilet. But the necessary adjustment is not the ultimate solution. You may need to replace your fill valve when it’s worn out. Also, blockages in the pipes and vent can alter the water level in your toilet bowl.

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