My toilet runs when the kitchen sink is running. I have replaced the fill valve and the flapper and have set everything to the correct heights/levels etc. Also, the toilet doesn't completely run a full flush without using a plunger, which is making me think clog somewhere. I should note a few things, one, the toilet is upstairs, while the sink is downstairs. Two, the toilet is almost 40 years old from the stamp in the tank (flush problem could be jets) and last but not least, we are renters and the house is over 200 years old. We have no idea how old the plumbing actually is. We will be replacing the actual toilet soon, but, I am wondering if the two problems could be due to the same issue and also if there's anything I can do before I give up and call a plumber.

  • 1
    What do you mean by the 'Toilet runs'? Do you mean that you can hear it filling, or that water is running into the bowl?
    – HandyHowie
    Commented Nov 28, 2022 at 10:13
  • I've seen a similar post on this site before but cannot find it at the moment. The issue occurs due to a pressure drop in the cold water line. Does your home have a proper 3/4" or 1" main supply line and then just a 1/2" leading to the bathroom? You can buy a hose bib water pressure gauge and see what kind of pressure drops you're experiencing.
    – MonkeyZeus
    Commented Nov 28, 2022 at 13:42
  • 3
    "We're renters", yet the landlord isn't fixing the issue for you?
    – FreeMan
    Commented Nov 28, 2022 at 13:57

2 Answers 2


You should call the plumber in. It sounds like you have a failed or failing Pressure Regulator on the plumbing system that needs replacement, this will likely need to be soldered in. Though, you can try tightening/loosening the screw on top of the regulator to see if you can get it fixed temporarily or even permanently...as street pressure may have changed over the years.

As far as the toilet not flushing, a new toilet would be very good. A lot of the time there's a cast iron drain pipe that has rusted itself to a much smaller diameter, which needs to be chiseled and vacuumed out to restore any old or new toilet's proper operation connected to it.


One thing I can think of is the water pressure change.

That could make the toilet fill valve to open.

Adjust the floater to bit lover position so there is more pressure on it in closed position.

  • Why would adjusting the float add more pressure to the valve? Wouldn't it just close the valve at a lower water level?
    – HandyHowie
    Commented Nov 28, 2022 at 10:09
  • @HandyHowie if more of the float is submerged, it will push harder (displacing more water). It will try to close lower, but might succeed around the current water depth. But I've never had much luck trying this
    – Chris H
    Commented Nov 28, 2022 at 13:19
  • @ChrisH That is the point, how can more of the float be submerged? The float will always rise until the point the valve is fully closed. Adjusting the float only adjusts the water level.
    – HandyHowie
    Commented Nov 28, 2022 at 13:49
  • 1
    @HandyHowie The point is that the valve isn't fully closing (or rather, might not be - I'm not convinced). That means a lack of pressure on it. The level in the tank is also limited by the overflow, so if adjusted too high the float will sit on this maximum water level without applying much pressure to the actual valve, and running water will be heard. Adjust it lower, more force for the same water depth. But I'd expect running the kitchen tap to reduce. not increase the pressure, so this probably isn't the fix
    – Chris H
    Commented Nov 28, 2022 at 14:03
  • @ChrisH I agree, if water is flowing down the overflow, but this is more likely a sign of a faulty valve which needs repairing rather than the float adjusting.
    – HandyHowie
    Commented Nov 28, 2022 at 15:24

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