I would have the RFID bracelet thingies keep track of whenever you enter the bathroom. After a certain number of entries in a day (3 if you're off property, 5 if you're on) you would be unable to flush, thus conserving water. Now, you may be entering a bathroom from time to time without using a potty, so there would be cameras scattered about recording. Since your RFID chip would record the time you entered the bathroom (say those tucked away behind Pirates of the Caribbean) you could call one of the bathroom monitors and say, "I know I'm at my potty usage limit, but if you watch the recording of my 9:53 AM entry into bathroom such and such you will see that I did not do any flushing of significance. I'm the guy in the blue blazer and the festive holiday tie." They could then credit your potty usage account with a credit re-enabling you to flush. Simple really. It would fix the parks by conserving water, forcing people to think before engaging in biological functions, and create shorter lines making "tinkle time" a more efficient experience for all.