My husband and I consume a lot of Diet Coke. In the evening when I am picking up after everyone I find half full or half empty (depends on how you look at it). I get upset when it is wasted and I have to pour it down the drain.
I did an experiment. I bought the plastic bottles that hold about 10 oz. When someone doesn't finish it goes back into the fridge. It worked! It also reduced the amount we were drinking each week. So two things were accomplished.
You can also try this with the large bottles. I think these taste better than the metal cans.
Try it and tell me if works!