Sweating Pipe

Lest you think Ted is slacking while I strip paint, rest assured he's been working on plumbing. Here he is in the garage "sweating pipe" for the new bathroom supply lines. His work surface is the old sink we pulled out of the bathroom. It's worked very well for him.

Calling All Housebloggers...How Do You Unclog Old Pipes

With all the long-haired hippie types living at The Box House, our drains frequently clog, even with hair traps over everything. Most of the time, a plunger will work, even for the tub. However, the time between clogs seems to be getting shorter.

The problem is, we have ancient cast iron pipes that are probably rough and rusty on the inside, making them perfect hair catchers. I'm loathe to use non-mechanical means to unclog, because I've been told that Draino and the like are too corrosive for old pipes. What's everyone else using? Our tenant suggested bleach, but the info I'm finding online is rather conflicted. Some plumbers say okay, others say no.

So, I'm hoping someone will chime in with their fail-safe, house-safe method for unclogging a drain. Thanks!