I just finished off part of my basement with a new bar that has 4 taps, one with a stout faucet on Nitro and the other 3 on CO2. The drip tray drains into the main sewer line for the house behind the wall. The drip tray also has a glass rinser with water supply. The keggerator behind the wall is a converted chest freezer that can hold 4 5 gallon kegs. There are 3 recirculating fans to keep an even temp throughout. 2 of the fans also recirculate cold air in the insulated PVC pipes that keep the beer lines cold going to the taps.
My old and smaller keggerator was converted into a fermentation chamber with a 2 stage temp controller that controls the keggerator and ferm wrap on the carboy. I installed 2 CO2 lines as well so I can cold condition kegs when not fermentation and carbonate at the same time so the next keg is ready when another one kicks.