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I had water going into toilet that would not cut off, changed the fill valve but still happens. When Shut off valve is OFF it still allows trickle of water into toilet back and then dribbles out the the overflow, with the shut off valve off takes about an hour. I guess I need to change the shut off but a friend said I could loosen the handle screw turn it back a bit and then re tighten so it could SHUT OFF more ??? IDK, I am afraid if I loosen anything I will have a flood since that little ball (if there is one) might fall out. I had to have the valve in the exterior faucet replace last month since it would not turn off completely either. I really hate to call the plumber back for something so simple. Maybe they are just worn out? House was built in 1986, I originally had those grey plastic pipes but they were converted to copper 20 twenty years ago ( at least I Hope they were all changed) Thanks in advance for any advice.

  • In the pipe that feeds water to the cistern, there might be a valve which can be turned with a screwdriver. Before I suggest anything else, do you have such a valve? Commented Sep 23, 2016 at 15:16
  • sorry IDK all I see is the shut off valve- the bendable hose and the nut that hold the fill in place
    – candy
    Commented Sep 23, 2016 at 15:23
  • everything I search for shows water leaking out of valve onto floor, that is not the problem, water is still running into toilet back of tank (is that what you meant by cistern) and my water bill was like $70 more than usual. and I just replaced the fill stack thing in the tank thinking it was that not shutting off.
    – candy
    Commented Sep 23, 2016 at 15:28
  • 3
    Those style of valves are notorious for failing (leaking) over time. The valve itself needs to be changed out really. You might be able to tighten it up but it will leak again eventually. I'd recommend replacing with a quarter-turn ball valve. Not a hard job.
    – topshot
    Commented Sep 23, 2016 at 16:28
  • 1
    I missed the part about water going down the overflow. If that is the case, the new fill valve you had put in is not working as it should and Shimon's answer should help you. If a plumber installed it, I'd be wary of calling that one back again since he should have verified proper operation. That being said, your shutoff valve still leaks, too, so you should do that at the same time.
    – topshot
    Commented Sep 23, 2016 at 19:56

2 Answers 2


There are three valves in and around your toilet:

  • The supply valve is what connects water from your home's cold water pipes to a hose or tube that connects to your toilet tank. This is what you have pictured.
  • The fill valve inside your toilet tank lets water into the tank (usually sending some to the bowl also) so it is ready to flush. These are designed to fill the tank to a certain level and then shut off. The common designs for this are the traditional ballcock style with a round float attached to a lever, and the newer style (popularized by Fluidmaster) where a plastic float slides up along a shaft.
  • The flush valve is what dispatches water from the tank into your bowl when you flush.

The valve you've photographed is the supply valve. It does sound like your supply valve allows some water through even when tightened, which is not good because you want a supply valve that shuts off water completely for service. However, the more significant problem is your fill valve. If the supply valve leak is slow, you may just be able to shut it of as best you can, have it drip into a bucket for a few minutes, make other repairs, and reattach it for normal use.

The reason we know the problem is your fill valve is that, even when the supply is fully open, the fill valve should stop the flow of water into your toilet tank when the tank is full. If that doesn't happen, the tank will be overfilled. To prevent water spilling onto your floor in that case, the tank is designed with an emergency overflow path that just drains overflow into the bowl. Nice to not have a wet floor, but you're still wasting and paying for a lot of water.

So the question then is: why is your fill valve not stopping the flow of water into your tank? Photos may help, but the common causes are:

  1. Incorrect adjustment. Fill valves can be adjusted to set the desired fill level, usually by turning a screw. If the level is set too high, it will never reach that level and keep filling while the overflow drains.
  2. Obstruction. The valve control can be blocked, either by mineral buildup on the valve parts or by poor positioning next to other toilet parts.
  3. Wear. Some fill valves include rubber gaskets/washers that erode over time, or can accumulate mineral deposits. Cleaning or replacing these parts, or sometimes simply tightening parts of the valve, can fix this. But often it's easier to simply replace the whole flush valve.

What to do next: We want to figure out where your fill valve is leaking, so let's try to control its operation so we can observe it.

  1. Take the lid off your tank.
  2. Open the supply valve.
  3. Standing over the toilet, gently lift the fill valve's float mechanism to the point where it should be shut off. Hold it there - the fill valve should stay closed.
  4. Hold the flush valve to drain as much water as possible from the tank.
  5. Identify where water is exiting the fill valve. This is your leak.

Depending on your type of fill valve, you may be able to repair the leak or it may be more practical to simply replace the valve. Post pictures and info on the leak if you want more advice. Good luck!

  • 1
    From experience, it is possible that the ball float is partially filled with water, so it can't exert sufficient force to completely close the inlet valve. Commented Sep 23, 2016 at 18:28
  • OK guys-Maybe, but I replaced FILL VALVE a few weeks ago since I thought that was the problem. It could be bad one. When SUPPLY VALVE is open the water fills the tank through the tube into what I called an overflow. Once it fills-water stops going thru tube but still comes into the tank through the bottom of the fill valve. If the supply valve is turned off, no water runs through the tube but tank fills from bottom of the fill valve. You can see the water moving
    – candy
    Commented Sep 24, 2016 at 2:23
  • When filling/filled lifting that floater does nothing, I thought it might not be tall enough but IDK. And I thought the water should stop when I turned off the supply valve. don't know how to "empty" float either, but doesn't seem to have water in it. But thank you both for your answer and any advice you can offer.
    – candy
    Commented Sep 24, 2016 at 2:23
  • The fill behavior you described is normal when the supply is open -- the fill valve will let water into the tank near the bottom of the valve, and a flexible tube going from the fill valve into the overflow tube adds water to the bowl (if it's going into that overflow tube, it goes right down to the bowl and does not contribute to filling the tank). Your supply valve is clearly leaky, but this shouldn't affect normal service - when your tank is full your fill valve should stop water flow regardless of the supply valve's state. Commented Sep 25, 2016 at 1:26
  • If you had the fill valve installed by a plumber, ask if they'll come back and fix it. Yes they should have checked, etc., but even a good plumber can make a mistake or have a part go bad unexpectedly. If they accept their mistake and fix it at no additional charge, they're still good. Commented Sep 25, 2016 at 1:28

I can help with the shutoff valve. Its also called a stop valve. Its made by Brasscraft. No need to get a new valve, just get a repair kit.


They cost a few dollars and Home Depot usually has them in stock. You will need to shut off the water supply to your whole house / apartment to fix it. Then remove the handle and the nut holding the stem in the valve. Put a new washer on the end of the stem and on the shaft. Tighten the nut snug so that the valve still turns.

That will take care of shutting off the water so you can work on the toilet. Some toilet field valves can be flushed out, especially fluid master ones. First try to remove the cap and see if it can be cleaned. If you buy a new one, get a fluid master.

  • @ OP, alternatively, loosen this nut he's talking about (not the screw in the handle; the nut just behind it) so that you can turn it off "more". Work the handle back and forth a few times to clear out the crud and then re-tighten the nut.
    – Mazura
    Commented Sep 26, 2016 at 21:34

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