Last night at about 1am, I heard running water that sounded similar to a washing machine filling up with water. I ran into my bathroom and saw water overflowing from the toilet tank (not bowl). I immediately shut off the water valve behind the toilet and took off the toilet lid. The fill valve had completely broken off at the base! I flushed the toilet to try to empty the tank, but the water was still coming up to the tank even though the stop valve was turned off; I could also still hear water loudly flowing through to the tank. The only way I could get the water to stop was to turn off the main cold water valve to the entire condo.

I have not done much toilet repair at all, but am I correct in thinking that the issue here is the stop valve? I initially thought it was a surge in water pressure, but now I am wondering if something simply failed in the valve, which caused the surge in pressure which broke off the full valve? The fact that I can't fully turn off water to the tank by using the stop valve alone seems to be an indication of the main problem.

Another possibly unrelated problem (or maybe related??) is when I turn off the main cold water to the condo, my shower hot water trickles out. A friend told me it could be a mixing valve issue, but up until today, we haven't had much problem with hot/warm water in our shower. Others in my building have had mixing valve issues.

I am in a condo that is about 10 years old so I know I am going to have to start replacing things! Just would like to know what and to see if I can do it myself.

  • 1
    Old valves do not always close completely. You may want to consider having that valve fixed (or, possibly, replaced).
    – keshlam
    Aug 15, 2016 at 8:27
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    Resolution: so here is what happened. The valve behind the toilet would not fully cut off water flow because the o-ring had failed. We did not know this was the case until the full valve suddenly broke off, which caused the toilet tank to fill and overflow. Water kept filling the tank even when we turned off the valve behind the toilet because of that failed o-ring. Fill valve broke because it's a cheap part and bleach tabs had corroded it. The entire part was brittle to the touch! So we replaced the fill valve and the water valve and all is good.
    – LC H.
    Aug 16, 2016 at 18:02
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    Regarding the shower, we still don't know what the deal is but have been told mixing valves are failing and we are required by our condo HOA to have them changed. We called Kohler and they are always great and send replacement parts for free! HOA charges $250 to replace for us, but we took it apart ourselves and it's pretty simple. Thabks everyone for your help!
    – LC H.
    Aug 16, 2016 at 18:04
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    Hey, thanks for posting your resolution! Unfortunately, it gets lost here in the comments. Either give a check-mark to one of the answers that let you to figuring out what happened, or copy/paste your comments into an answer of your own and give that a check mark! That'll help everybody, especially those looking to solve this kind of problem of their own.
    – FreeMan
    Aug 21, 2020 at 20:49

2 Answers 2


It's fairly common for gate valves to fail, causing them to not open or close properly. In this case you can either repair them (most of the time), or replace them. If you're replacing them, I'd recommend installing a ball valve instead.

I'm not sure what could have caused the fill valve in the toilet to break off. Without a photo or two of the broken valve, it's difficult to even speculate what could have caused it.

As for the trickling hot water... It's not clear if you mean it always trickles out, or trickles out when you open the hot water valve. If you mean that it trickles out when a hot valve is open, that's completely normal. If the main water supply is turned off, there's no pressure to push the hot water out of the tank. Remember, the hot water tank is supplied by the cold water supply line.

Without being able to come on site and investigate, it's difficult to say for sure what's going on. Obviously, you'll want to replace the broken fill valve. You'll also want to repair, or replace the shutoff valve for the toilet. If you don't have the tools or knowledge to do so, you might want to have these things handled by a plumber.

You also might want to investigate whether or not there's a pressure regulator installed on the main water supply line. If there's not, you might want to consider installing one. If there is, you'll want to make sure that it's set, and working properly.

  • Thank you for your response. I plan on replacing the washer, the valve (to a ball valve) and the fill valve. RE: the trickle of hot water from the shower, I did not turn off the main water supply. I don't believe I have control over that in a condo? All I did was turn off the cold water valve. The hot water press works fine at my kitchen sink (1 handle for h and c) and ba sink (2 handles). Is it still normal for hot water to trickle out when the hot water valve is open and the cold valve is closed? When both are open, we are getting enough warm water during showers. Thanks!
    – LC H.
    Aug 15, 2016 at 16:22
  • @LCH. Sorry, I didn't realize that your condo was fed by separate hot and cold supplies.
    – Tester101
    Aug 15, 2016 at 20:34
  • @LCH. "Is it still normal for hot water to trickle out when the hot water valve is open and the cold valve is closed?" Yes, if you have thermostatic anti-scalding mixing valves.
    – Dan D.
    Jan 24, 2017 at 12:21

If you turn a valve off on a toilet and water continues to run this problem is caused from a failed washer in the valve. These are usually easy to repair and cost less than a dollar for several sizes. The failure of the tank float valve could be caused by pieces of the washer getting stuck in the float valve but if broken off ??? I have not found a float valve broken off even with pressures as high as 100 psi. With higher pressures they do leak more often and fail sooner. If you turn the main valve to the condo off and open a hot water valve to dump the pressure in the tank no water will flow if the main valve is good. With the main cold turned off the water heater on can create pressure and even burn out in some cases if not turned off.

  • Thank you! My main water valve is still on, only the cold water valve is off. We use water still, just try to wash hands really quick before the hot water turns hot! Do I only risk burning out the water heater if the main water valve is off? Thanks!
    – LC H.
    Aug 15, 2016 at 16:24
  • It depends on the water heater. I have replaced quite a few the owners turned off the water main but not the water heater. If there is not a pressure switch they try to keep the water hot once the water is gone they fry the element and usually crack the tank.
    – Ed Beal
    Aug 15, 2016 at 16:33

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