Regarding the leniency to use a towel on Shabbat - leave it to dry over a windowsill. The main concern is for wringing it out - and that isn't such a concern. Also - Stealing applies to Shabbat. Though of course the conclusion is that you don't get to claim stolen property on Shabbat. Plus - How to treat waste water, given the eruv permutations, on Shabbat. Dumping waste water via the hole in the floor of a balcony over water? Dumping into a pit in the yard? Dumping into a pit outside your private property? A drainage ditch? What about seasonal differences? But if you can't pour directly into a ditch - you still can use a roof and let the waste water slide right off.