We have three toilets in our house. Our house was built in 1999, so they're the more recent smaller-tank models.
When we moved into the house in 2007, we had the innards of two of the toilets replaced. The house had been vacant for a few months, so we found that there were small leaks, most likely from seals that had been dried out from not having been used.
In 2008, I replaced the innards of the third toilet, having noticed a small leak developing.
I've found that the best approach seems to be to replace the entire guts of the toilet rather than fool around with trying to identify the specific part that is causing the leak. The cost for doing the entire toilet is around $22 and I figure it's worth replacing everything because if you try to replace one specific part, you're not only taking the chance that you get the right part the first time, you're also taking the chance that, even if you fix it, that another piece of the mechanism won't fail.
The stuff that you buy is pretty much all plastic these days. We got ours at Home Depot. I know it isn't the highest quality stuff, but it's not cheap either. In any case, I'd expect it to last a few years.
So, I was surprised when I noticed a slight problem with one of the toilets that had the work done in 2007, three and a half years ago.
After a flush, I noticed that the toilet seemed to be running longer than normal. Usually this means that the flapper doesn't close, and that you need to jiggle the handle. This time, though, when I looked inside the tank, it actually was at a high level but not shutting off.
The float, which in the model of innards we have is not free-floating but is attached vertically surrounding the main piece, didn't float. It was ‘stuck' at a lower position. When working properly, the float rises to the correct level, shutting off the water level. Since ours wasn't rising, the water kept going. There wasn't a flood danger, it was just wasting water. And, if I hadn't of caught it, this could waste a lot of water.
I ended up moving the float around, trying to perhaps loosen any deposits that might have formed. So far, the problem hasn't repeated itself, but I'd be somewhat disappointed if I had to replace all the innards after only three and a half years. I have five or six years in mind as a ‘reasonable' amount of time.
What do you think is a reasonable amount of time between changing out the innards of a toilet? Have you ever run into the particular problem that I'm describing, and if so, are there any other fixes other than replacing the guts again?