I have hanging toilets built into the wall from Geberit (like these), which I installed 5 years ago. I only started using these toilets one year ago and noticed the water coming out was pretty dirty. When I opened the back I could see a lot of dirt caked on the inside of the toilet.
I traced this issue back to the fact that this water is rain water, and that the rainwater well had also been stagnant for 4 years (and it probably hasn't been cleaned in more than a decade). There were filters installed for the rain water, but those were pretty dirty and (you guessed it) were not replaced for 4 years.
Is there a way I can clean the inside of my toilet? I replaced the filters already and I am also planning to clean the rainwater well in the summer.
I tried pouring in vinegar, but that did not work, as I think this is organic matter and not some kind of deposit because of hard water. I think I may need to use some kind of bleach, but I am hesitant to do that as I don't know whether my toilet can handle that.
Pictures (not really visible I know):