I agree, jdef.

I've just consulted with an expert in the field, my son, who is studying to be a Plumber. No kidding ... it takes a hell of a lot of study to become licensed in this day and age. After I waded through the internet and all kinds of informative web sites, I found he had the same answers - and a LOT more - "off the top of his head".

In the future - those with all kinds of higher degrees from prestigious institutions will be completely at the mercy of the only ones who will know how to repair a toilet ... the Plumbers.

One minor correction to your post ... common table vinegar is approximately 5% acetic acid ... I routinely cut that 1:4 with water ... to a concentration of ~ 1%. Even less "damaging". Of course, if we were on a crusade to keep acetic acid completely out of the environment ... we would have to eliminate ALL fruit trees.