There is usually one or two pipes per house that take out your non-toilet water and deposit it into the drainage trench beside your house, then on into the street system. These pipes get clogged with hair, scum and soap deposits that can block it completely, and cause a flood in your downstairs bathrooms, as well as very slow drainage from all bathroom and kitchen fixtures.
It may be old news to many, and you may laugh that I didn't know, but the way to stop the problem forever is to stop using bar soap to wash with. Bar soap does nothing but build up scum (like on your shower walls and floors) and causes major clogs in your drainage pipes. Liquid shower gel and liquid soap does not. Apparently a totally different chemical formula than bar soap. The same goes for laundry soap, switch from powder to liquid.
So now I know, and after six months I can confirm we have clear pipes and clean shower walls/floor by stopping the use of bar soap completely. In the past I was outside every two months with my head in a trench trying to ream out clogged pipes with a water hose and metal probe, no more. In this case, old dog learned new trick.

