There is a pool on top of the Jewel at Broadway and Montrose. It is part of the World Gym, not sure how their memberships work.
The pool is part of Pensacola Place and the World Gym has limited access to it.
Let me introduce you to the best kept secret in Uptown, the Uplift community pool.http://www.chicagoparkdistrict.com/resources/pool_schedules/pdf/Uplift.pdfAdult lap swim every Saturday morning from 9-11am, and it's typically pretty empty(I think that's why it has such short hours). You can also swim laps during Open swim(11-1), but there could conceivably be a ton of kids in there(although I've never seen this happen)