I could see really hard water and really old plumbing eventually having issues. In my opinion, most households can handle regular usage of homemade soap without stressing that they might be damaging their plumbing. But hey, like you said, why not use a lower SF and chelators to minimize risk and save yourself some elbow grease! Speaking of which, I’m going to search the forum after work to see if there are any threads where people share how they clean soap scum..
Yes! Lol, There may be no such thing as “perfect” soap, but you know what, I’m going to keep on trying!!
A person can dream, right? ☺