I start with a 20 oz insulated cup and fill it to the top with ice, then add what soda it takes to top it off. I had bad tasting well water, so I bought bagged ice. In fact, I bought more ice than soda. I have to watch how much i drink, because of water retention swelling my feet an ankles, and balance that against the constant thirst caused by the diabetes. A 2 liter bottle would last about two days, unless the shop hit over 90 degrees and I was losing a lot of water as sweat.