I'm no plumber, but I jus gotta say;
My wife takes a lotta showers, and loses a lot of hair, and every time she does, some of it settles in the traps with the soap scums. About once every four years or so she will be standing ankle deep in water, and freaking out. To make my life easier,I have engineered lots of slope and short runs to the stacks, jus saying. And it still comes about every four years.
Up here where I live, the drains have little openings, about quarter by quarter,and are flush to the floor, and are retained from the bottom; so good luck fishing the hair ball outta there.
When it stops draining, who's gonna be the lucky guy to tear it all apart to clean it out, jus saying.
But I'm no plumber.
