How Do I Adjust a Toto Toilet?

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The TOTO brand is known for creating luxury toilets with numerous features and settings aimed at reducing water waste and improving your bathroom experience. However, TOTO also offers a regular toilet with a lifted tank that combines G-Max flushing technology with a special glaze on the bowl to clean the toilet with each flush. Adjusting a TOTO toilet's G-Max water fill valve ensures the appropriate amount of water fills the bowl and tank. Too much water in these areas could waste water, whereas too little might not allow the toilet to sufficiently flush.


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Adjusting the Tank's Water

Your G-Max (also known as Korky, the manufacturer of G-Max) water fill valve contains a device called a float that tells the water supply to shut off when the tank is full. If the valve is located too far down in the toilet, not enough water will fill the tank, and water from the refill hose may have trouble emptying into the overflow pipe. If the fill valve is too low or too high, you can easily adjust it.

Start by turning off the water supply to the toilet and holding down the flush handle to drain water from the tank. Unclip the refill tube from the overflow pipe. Next, turn the entire head of the water fill valve counterclockwise to unlock the vertical adjustment function. Lift or lower the head of the water fill valve until the bottom of the top cover lines up with the top of the overflow pipe or with the water level mark on the overflow pipe.


Rotate the valve clockwise to lock this position in place. Reattach the fill tube to the flush valve pipe. You can now turn the water supply back on and allow the tank to fill.

Adjusting the Bowl Fill Volume

If the fill valve is at the correct height but an inappropriate amount of water continues to fill the bowl, there may be something wrong with the restrictor.

To understand how a restrictor works, it's important to understand how toilet tanks work. The water supply to the toilet turns on and runs continuously while the tank fills up. The water will continue to run, filling both the tank and the bowl, until a mechanism called a float confirms that the right amount of water has filled the tank. This means water will flow into the toilet bowl during the same time frame that water fills the tank.


A restrictor allows only a small amount of water to pass through the fill tube to control how much water enters the toilet bowl during this time. If too much water is in the bowl, a smaller restrictor is required, but a larger restrictor (or no restrictor at all) is necessary if there's not enough water in the bowl. Flow restrictors typically attach to the hose leading from the fill valve to the overflow tube, but this fix may require a plumber for best results.

Luxury TOTO Toilets Are Different

Note that luxury TOTO toilets with a partial flush feature use a different float/valve device altogether. Consult your owner's manual to learn how to adjust the amount of water used for partial and full flushes since the specifications vary based on each TOTO model.



Cathy Habas enjoys distilling even the most complicated home improvement tasks into bite-sized pieces. She believes in empowering homeowners one article at a time.

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