We have a Gerber toilet in our master bathroom and when you flush it, it empties the bowl twice.

Is there a way to adjust the flush valve so that it only flushes once per cycle?

Our other toilets, same brand, work as they should.

toilet tank internals

  • 1
    your floater is stuck
    – Traveler
    Aug 26, 2023 at 19:22
  • @Ruskes Would you mind expanding on that in an answer?
    – matt.
    Aug 26, 2023 at 19:26
  • 1
    I have found that, for most toilet problems that are in the tank mechanism, the best answer is "don't bother debugging it; buy a universal toilet tank kit, and replace every component that looks old until the problem goes away". Aug 26, 2023 at 19:31
  • 1
    With lid open observe
    – Traveler
    Aug 26, 2023 at 20:37
  • Might the vent stack be plugged, such that the water going down the drain could be pulling the water out of the toilet's trap? Aug 29, 2023 at 1:36

3 Answers 3


You need to look at the toilet bowl and tank and observe what exactly is happening.

The tank doesn't really DO anything to "flush" the toilet. You can flush it by pouring enough water into the bowl.

So the question really is, why is there so much water going into the bowl, to flush it twice?

There are multiple causes to this:

  • flapper is stuck open too long
  • float is set too high so overflow water fills the bowl
  • fill tube refills bowl with too much water
  • plumbing issue further down the pipe and creating a vacuum to siphon your bowl

Observing the tank and bowl in a flush will give you more details as to the cause of it.

enter image description here

  • The flap is getting stuck, and does not come back down. I'll get a new one. Bounty awarded.
    – matt.
    Aug 31, 2023 at 16:49

The toilet bowl flushes by water rushing into the bowl, pushing water down the hole and creating a siphon. The tank simply holds the water, dumps it quickly into the bowl, and refills itself.

To narrow the problem down, quickly pour a bucket of water into the toilet and see what happens. If it still happens, then you have a problem in your drain pipes and don't have to keep messing with the stuff in the tank.

  • Flushes once with a bucket of water.
    – matt.
    Aug 31, 2023 at 16:48
  • OK. Next step is to do as others have suggested and watch the tank internals when you flush. Does the flapper at the bottom of the tank double tap, dropping water twice, or is it one continuous flow across both flushes?
    – Frank
    Aug 31, 2023 at 17:14

Sounds like to me that the flipper is getting wage to the side or is damaged until enough water gets on top of it to push it down so I would check the flipper just to be on the safe side if that doesn't work double check the amount of water in the tank versus how much water is used to actually flush it should be around about one gallon or 1.5 gallons

  • When you flush it the one time is there water in the bottom part of the toilet that's supposed to fill up that part is there water in there or does it seem like you have to press the lever to let the tank drain into the bottom of the toilet to refill seems like there's not enough water getting to it may need to adjust the float the white bubble the big bubble adjust it to where it will rise up a little bit more so that it will increase the water in your tank to add more water to the flush
    – bugjr2
    Aug 31, 2023 at 8:37
  • 2
    "Wage"? Do you mean "wedged"? Also, please capitalize and punctuate your sentences so you're more readable.
    – isherwood
    Aug 31, 2023 at 13:15
  • 1
    Please make actual sentences one long run on sentence is really hard to read and understand what youre talking about I mean its just kinda stream of consciousness writing and thats ok if youre a writer and trying to get the creative juices flowing but if youre trying to provide clear concise instructions to someone so they can fix a problem it doesnt really work so well
    – FreeMan
    Aug 31, 2023 at 16:18

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