I still can´t drink 2 liters of water a day, but this is what I do to help me know how much I´ve been drinking. I have a 50 cl. bottle of water near me all the time and I drink from there. I keep refilling the same bottle, that way I know how many bottles I need to drink in one day. If I drink 2 bottles I know I had 1 liter an so on.