We got a lot of stuff done around the new house this weekend. I started off with what I thought was going to be a fairly simple project. The toilet on the main floor would run every couple of minutes. You could see the water level drop in the tank, the float would drop, the valve would open, the tank would fill, and it would all repeat. Very annoying. And pretty straightforward to fix, so I thought.
There's no water on the outside of the toilet so the water draining from the tank has to be going into the bowl. The only way for water to get from the tank to the bowl is through the fill tube or the flapper. I bought a new fill tube and flapper and installed it. Done and done. Except a few minutes later it was running again.
Now I'm confused. Take everything apart, inspect every sealing surface, and reassemble. Still not fixed. I proceeded with several theories and scientific experiments but nothing seemed to be solving the problem. I even had the tank sitting over the kitchen sink so I could observe any leaks. Everything seemed to work except when it was installed on the toilet.
My best guess was that the fill valve had been replaced at some point with a lower water volume model. Lower fill line means less water pressure on the flapper which means less of a seal. I broke down and bought ANOTHER fill tube and flapper but one that's designed for a smaller volume tank.
I installed this contraption in the tank and nearly lost my frigging mind when I heard the toilet running two minutes later. I was almost weeping as I looked to the internet for any possible explanation. And google delivered! Turns out the hose running from the fill valve to the fill tube was too long and was actually siphoning water from the tank into the bowl.
I snipped the hose to the right length and everything has been great. All that disassembling and reassembling and all I had to do was cut a hose to the right length. Frig me. But three cheers to the internet for saving me from going absolutely bonkers.