Is there anything to try or does the fill valve just need to be replaced?

A toilet with a floatless fill valve isn't fully closing and is filling past the overflow tube (blue circle in image):

enter image description here

I have adjusted the adjustment knob (red circle) as much as possible to lower the water level. If observed closely in the image, the diagram at the right of the valve indicates to turn clockwise to "raise" or counterclockwise to "lower" the water level. Turning it completely counterclockwise essentially closes the valve and causes the water not to fill at all or to fill very very slowly, however it does not seem to adjust the water level as much as I need.

To my recollection, even when this valve was brand new it was difficult to get the adjustment right. It brought the water level to the edge of the overflow tube, but over time it has gotten higher, at first barely seeping over the top, and now it's overflowing constantly.

Another thought was to try to add some extension to the overflow tube but that might be more trouble than it's worth.


2 Answers 2


The internal gasket/diaphragm needs replacing, check out this link.

It does appear that you could extend the flush valve overflow tube as the height appears to be below the water level mark on your tank. That mark is actually the right level for optimal flush performance for your toilet. If the valve is worn out it may not help though, although the weight of the additional water may get it to stop. You might try opening the valve up and gently rinsing the gasket, in case there is debris or build-up interfering with proper operation (turn the water supply off first!)

  • What would be a good/easy way to extend the overflow tube? Now that I think about it, I believe the current tube was part of a replacement kit (fill valve + flapper + etc) that had a shorter tube and valve setting for water savings. The floatless fill valve is more recent. That might explain why this fill valve always filled too close to the rim of the overflow tube, even when it was new.
    – adatum
    Commented Sep 9, 2017 at 1:35
  • Sometimes a 3/4" PVC coupling fits (just glue it with caulk, not PVC glue cuz high solvent glue could soften the thin OF Tube). If not, try sliding on a short piece of heater/radiator type hose, or other stiff hose. The problem is the refill tube, dont stick it down the extended OF pipe, youlle need to figure a way to keep the end above water level. Old-school flush valves were brass with a replaceable copper OF tube... alas no more. Commented Sep 9, 2017 at 2:19
  • If it flushes OK now, don't worry too muchabout the OF... you need to repair/replace that fill valve. BTW those Fill-pro valves are a bit notorious, reliability wise. Commented Sep 9, 2017 at 2:21
  • Currently that link goes to a 12" pipe wrench. That's probably not the original result, but made me laugh
    – STW
    Commented Jan 8, 2020 at 2:14
  • @STW, lol perfect example of fallibility of links and why they are discouraged as a substitute for explanation on this site. That used to link to a Fill-pro fill valve replacement gasket kit... Commented Jan 8, 2020 at 2:19

Partial solution was to disassemble the fill valve and rinse the diaphragm and internals with water and vinegar to remove hardened gunk. This improved the filling rate of the tank.

I also noticed an indentation in the rubber stopper in the valve that is used to block the water nozzle (see diagram below). Due to asymmetry, rotating the circular rubber stopper 180 degrees allows a "fresh" part of the rubber stopper to contact the nozzle. With no more indentation, the valve can close with less travel. Thus the adjustment knob is more effective now, and can close the valve at a lower water level in the tank.

Not sure how long this will last before the fill valve needs to be replaced, but the water is not spilling over the overflow tube anymore!

Now the flapper broke where the chain attaches to it, but that's another story...

enter image description here

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