Adjusting a Dual Flush Toilet

Dual flush toilets are great for those homeowners who are concerned about the environment and want to use less water. They’re also helpful for saving money on your water bill. In some municipalities, they may be required in new build bathrooms.

These toilets have a button mounted on the top of the tank that allows you to pick the size of your flush. The lower setting typically uses just under a gallon (3 liters) for a flush, while the higher setting is 1.6 gallons. Compare that to the older toilet styles that used 5 gallons per flush, and you can see where the savings come in.

Learning how to adjust a dual flush toilet isn’t difficult, and is something that the owner of one of these eco-friendly toilets will face at one time or another.

Remove the Dual Flush Toilet Lid

In the majority of these types of toilets, you will have to unscrew the push button, located on the top of the lid, before you can lift off the dual flush toilet lid. Try unscrewing the button counterclockwise. If that doesn’t work, or the button doesn’t want to unscrew, press down on one of the flush buttons. Then pry off the opposite flush button from underneath. Repeat the process for the first flush button. The flush button assembly should now be able to be unscrewed.

Adjust the Level

Adjusting the water level in a dual flush toilet is pretty simple. These toilets use an integrated float assembly that raises and lowers with the water level to control the water flow. The float is the ring-shaped device that fits around the fill valve in the left-hand side of the toilet.

There are two ways to adjust the level, depending on the valve. One is by a screw that sits on top of the fill valve assembly. Tightening this screw clockwise lowers the water, while loosening it counterclockwise allows the float to rise higher as the tank fills. The other way to adjust the water level is by pressing together the two sides of the lock that attach the float valve to the fill valve assembly rail mounted on the side.

If you are raising the water level, don’t panic when you start adjusting the water level in the dual flush toilet and you hear and see water begin to fill into the tank. That’s normal. The water will shut off when it reaches its new level. Likewise, if you are lowering the water level, you won’t see any changes until after the next flush. Which is the next step.

Flush the Toilet

Flush the toilet by pressing down on one of the buttons on top of the flush valve in the center of the toilet. Water will exit the tank and then refill. Check the new level. If it is still not at the correct level, make further adjustments. Flush as necessary to check.


Once you are happy with the water level, replace the lid. Screw back in the dual flush assembly and press the buttons into place if you removed them. Now that you’ve adjusted your first dual flush toilet, make similar adjustments to other dual flush toilets in your house as needed.

Read also about dual flush pros and cons here.