We have a standard household toilet—in fact, we have two of them. They both look exactly the same, but one of them doesn't stop running water. The float rises to what seems like its top position, but it doesn't quite shut off the water flow. In both toilets, the white hose points into a small central hole where the new water flows in. Is there a small adjustment I can make to the toilet where the float rises—maybe just a millimeter or two more—to fully close off the water flow?
Chat GPT 4
Yes, based on your photo and description, it looks like you have a Fluidmaster-style fill valve with a vertical float (sometimes called a "float cup"). If the float rises but doesn’t quite shut off the water, there are a couple of easy adjustments you can try:
1. Adjust the water level using the float adjustment screw
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Locate the small plastic screw or knob on top of the black vertical shaft next to the float (near where the float arm slides up and down).
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Turn the screw clockwise to raise the float level slightly (which should allow the float to rise higher and shut off the water).
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Only turn it 1–2 full turns, then flush and let it refill to test.
2. Check the float for smooth movement
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Make sure the float can slide freely up and down the shaft. Sometimes, mineral buildup or friction can cause it to stick slightly below the shutoff point.
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You can gently lift the float by hand—if the water stops running as soon as you lift it a bit, it’s definitely a height issue.
3. Confirm the fill hose (white tube) is correctly placed
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The white refill tube should direct water into the overflow tube, not below the waterline. From the photo, it looks okay, but make sure it's clipped above the overflow.
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If it's underwater, it could create a siphon effect, preventing proper shutoff.
Optional: Lower the entire valve assembly (if all else fails)
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If your tank's water level is consistently too high or low, you can usually adjust the height of the whole fill valve by twisting and lowering the assembly at the base (you'll need to shut off water and drain the tank first).
Would you like a step-by-step guide on turning the screw or adjusting the whole valve?
