You know I'm stretching for content when I write about a toilet. *lol* When we redid the bathrooms several years ago we decided on one-piece toilets where the bowl and tank are connected. Everything was great until we noticed that the one by our bedroom would randomly fill in the middle of the night. It would do it only once and then perhaps not again for days. It also seemed to do it only during summer. I thought that perhaps slight seasonal changes in water temperature were causing something to loosen over time. Since there was no leak on the floor, it couldn't be the fill valve. It must be the flapper valve. All of the screws seemed to be tight. *shrug* I forgot about it. I should mention that at some point I found a small metal "L"-shaped piece in the bowl. I thought it was from something that broke and tossed it. The random filling problem got consistently worse. It got to the point where it was topping off every 15 minutes or so. Even if it was only refilling a cup, at once every 15 minutes, that would be 5 gallons a day wasted. So I disassembled the flapper valve and found that since it was a one-piece tank, the valve was attached to the toilet by a flange/gasket that was held in place by 4 little "L"-shaped "hooks" that were tightened by screws. Only now there were only 3 of them. D'oh! That was that little metal part I had found earlier! It must have come loose and found its way down into the bowl. So I tightened down the other 3 screws/hooks as best that I could and hoped for the best. Nope. 3 wouldn't do it. Eventually the screws would loosen and the toilet would leak. I tried finding the gasket at our home improvement stores, but it was a specialty part. I called the manufacturer, and after a lot of back and forth trying to describe what I needed I finally got a part number. They wanted $90 for it. WTF?!? That's 20% of the whole toilet!!! I was able to find a slightly cheaper one on Amazon, but it was still ass-rapingly expensive for what it was. So I installed the new one and quickly dropped one of the "L"-shaped hooks down the toilet. D'oh! I tried retrieving it with a magnet, but it was made of brass. D'oh! Luckily I had the 3 from the old one. I quickly installed the new one and...it leaked. D'oh! But this time I noticed the leak was above the flange and just below the flapper valve. So back to Amazon I went. The flapper valves were much cheaper. A few days later I got the new valve, installed it, and...silence! Ah. The joys of home maintenance.