I am trying to do this but I can't get the "go 5 days without deep drinking" to start. Do you have to take a deep drink first and then stop? My Sim has never taken a deep drink so maybe the timer do...
Okay, this is a weird one. I've noticed if you fill your thirst meter completely, no matter how you do it, it resets the counter. Even if you drink plasma packs, plasma janes, and/or eat plasma fruit, it will reset.
The solution is to just not fill it. Stick with keeping your thirst bar at no more than 3/4 full but make sure it doesn't go into the red.