The toilet is completely dry. When it flushes normally, it stays dry. On occasion the toilet will not turn off and continue to run (I've checked each part and cannot find a reason why it would run once in a blue moon but turn off normal 99% of the time). So when it does run and we don't notice, the toilet leaks. I experimented today to see where the water was leaking from. It leaks so bad that it comes through our kitchen ceiling if we don't catch it in time-like flushing before bed!

I let the toilet run and let the water rise and go into the overflow valve. Within a few seconds, I felt a few drips of water coming from the nut that onnects the supply line to the tank. I immediately stop tank from running and leak stops.

I don't know if it's a loose nut or not as I can't feel anything or get to it easily enough (a wall is right there).

So my question is if it's a loose nut, why does it only leak when the toilet runs? Why doesn't it leak when we flush and it stops normally?

Is it because in a normal flush there isn't enough water going in to tank to cause a leak, but since the toilet is running, more water is coming in, causing enough to start to leak?

I'm worried about attempting to tighten and or having to replace the supply line and-or the nut as I don't want to break anymore seals and cause a weaker connection if I have to fuss with the whole supply line and fill valve.

Thanks!

The fact that your toilet keeps running/filling means your float and fill valve are not functioning. You can replace it for about $12 with a Fluidmaster 400a. It may only leak when the weight of the water in the tank reaches a certain point.

Agree, the water has increased pressure the higher it is in the tank ( they used to even have a valve that worked off the pressure instead of a float.

But agree, it is the float and valve that is the issue for running every now and then,

Replaying it, will also replace the seal at the bottom of the fill, so it will solve all issues.

We have the same problem and I'm not sure either how it happens. The float actually never engages because the flap doesn't fully seal and so the water is constantly flowing and that's when we get the drip. I find it hard to believe that it's the weight of the water or pressure of that weight in the tank because there is actually no water in the tank when the drip occurs... I am completely perplexed.

we have the same problem Every problem's a little different just saying " I have the same problem" addresses some else problem, I'm interested in yours.

the flap doesn't fully seal Why? Is the linkage too short? Bad flapper? Faulty flush valve?
You keep referring to a drip but give us no clue what's dripping or where it's dripping from. Can you post back with more information? Thanks, Tom