I have a standard, normal flow toilet, with a problem. When the toilet is flushed, it seems to start refilling the bowl with water from the tank too soon, before the waste has had a chance to drain away.

The result is that the toilet paper/waste just kind of floats around and doesn't really get sucked away. Only when it's sat for a while, soaked in the water and thus got heavy enough to sink does it reluctantly flush away.

Is there anything I can adjust to fix this, or is just a poorly designed toilet/components?


3 Answers 3


Actually, that's how a toilet is supposed to work.

You can simulate a flush simply by dropping a couple gallons of water in right away.

enter image description here

The spray paint fill is the natural water level. Flushing occurs by suddenly dumping excess water in the bowl. This raises the water level at the back, an a siphon effect comes into play with pulls the remaining water out of the bowl, giving the typical whirlpool effect.

If you're not getting the whirlpool, and a clearing flush, there are two possible scenarios.

  1. The tank isn't full, and not enough water is coming down to clear the bowl
  2. There is a small blockage in the drain.

But timing isn't an issue.

  • Interesting. I'll check the cistern and see if it's full. I don't think there's a blockage, but something makes a godawful noise when we flush, which stops if we run a tap (faucet) while the tank refills. Could that indicate something? Commented Oct 13, 2012 at 13:17
  • Get a bucket of water and dump it right into the bowl. If the toilet flushes normally, then it's up in the tank. The noise you're talking about sounds like a constriction in the inflow, which is most likely due to the valve not being fully open. But i believe that to be unrelated to the flushing problems. Commented Oct 13, 2012 at 14:03
  • It's a deep groaning sound somewhere in the wall. I've just let the cistern fill up as much as possible and flushed but no dice; the stuff in the bowl moves up not down when flushing, like its filling faster than it's draining. But it always returns to the same level overall. Commented Oct 13, 2012 at 14:46
  • Deep groaning sound could be vibration in the pipe (singing pipes) due to valve not being fully open. Check your shutoff valve and make sure it's open fully. Commented Oct 13, 2012 at 17:31
  • @TheEvilGreebo the shutoff valve being the valve controlling the flow of water into the tank? Commented Oct 13, 2012 at 17:37

Sounds like it's not using enough water in the flush.

You can adjust how full the tank gets, usually with a small screw where the float attaches to the vertical filling tube. You just need it to shut off before the water gets high enough that it starts going down the "overflow", at which point it would just try to fill forever.

When the flush stops is typically done by the chain attached to the drain flapper. Shorter chains will cause it to dump more water before closing. Just watching it in action once or twice should show you how your particular toilet operates and a bit of trial and error will make it clear which way things need to move.

  • The cistern is as full as it can be, about 7 litres, and drains almost fully when flushed. Commented Oct 13, 2012 at 15:38

In addition to the tank fill level discussed in Brian White's answer, there is another way to adjust the timing.

The common flapper has trapped air inside of it. When it is lifted by the chain, it floats in the tank water until the water gets low enough, and then it drops onto the flapper seat and stops the flow.


Different brands of flappers have different fall rates. I was having the same problem and I changed brands and it was solved.

There are also adjustable flappers that lets you change the air volume or add an extra float.

adjustable flapperadjust korky

This changes the timing of the fall and the amount of water in a flush.

There are a few specialized flapper designs, so be sure you check the type in your tank.

Note that American Standard has a proprietary flapper that has a water filled chamber that hold the flapper open. There is a hole in the chamber that drains and when it is empty, the flapper falls.

am std flapper

Finally, there are some new systems that let you have a dual flush - you can choose between high volume and low volume.

dual flush

  • None of these look like what I have in my tank - I'm in the UK, so perhaps the standards are different. I think that instead of a flapper we have a syphon, like this: toiletparts.co.uk/toilet_syphons_26.html# Commented Oct 13, 2012 at 17:36
  • Now that I think of it, it could be the diaphragm in the syphon that's worn and not making a good seal... I'm an idiot Commented Oct 13, 2012 at 18:13
  • @ElendilTheTall Don't know UK systems, but hte diaphram looks like a flapper. Some old styles in the US were lifted straight up and down on a brass rod going through eyelets.
    – bib
    Commented Oct 13, 2012 at 18:17
  • I believe the syphon works by creating a vacuum, and the diaphragm is necessary for that. Commented Oct 13, 2012 at 18:48

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