You have to remember she isn't drinking to fill her tummy, the food is doing that now. If her diapers are wet and she doesn't have signs of dehydration, or dry lips and skin then I wouldn't worry. I know that my son needs reminding to drink more because his lips will get dry and sore, I'll ask him how much he has drank in the last 2 days and he'll tell me Milk in my cereal, milk at lunch & water at dinner (but his cup at dinner is usually still half full). So I have to remind him that's why his lips are ready to fall off, to go to the fridge and get a drink of water. This happens every 3 months or so.
If you are that concerned teach her how to have a tea party, buy her a little tea set and put the water in it then you both get water and snack. Kids love to put water in little dishes it's something diffrent, and if they are taught that it can only hold water because we don't eat on the carpet then they usually only use water. (kids will be kids though). Just remember when cleaning little dishes and tea sets that they are always full even if they haven't played with them for days, because they will fill them and forget, then you'll clean them up and spill it. Have fun! J.