My Dear Pogo,
You can drink whatever you want! Unless some doctor said, "Don't drink anything else except water," then continue to drink whatever it is you like, along with water. I drink coffee, milk, orange juice, Canada Dry diet ginger ale, water, and sometimes iced-tea or lemonade. For lactose-intolerant people who can't drink milk, there is a milk product called "Nu-Trish" for them. I only drink a very small glass of orange juice in the morning and I only drink one cup of coffee a day. I drink ginger ale throughout the day, it has no caffeine. There are some sodas that are also no-salt and no-caffeine, which is Diet Rite, they have different flavors, all of them good. And every time I brush my teeth or feel thirsty, I drink a glass of water. I drink several glasses of water daily, but that's not all I drink. I drink a bunch of stuff. I love milkshakes from the fast food place and an Orange Julius from the mall sometimes.
The above poster mentioned caffeine-free tea, which is a great idea, and you can add ice and sugar to it, tastes good, and it's about the mildest watery drink you can have. If you really are on a water-only diet, you can squeeze some lemon in it with sugar and ice, or mash up some mint leaves and put them in there with sugar and ice. Did the doc really tell you to only drink water? Or have you gotten it mixed up and you think you can only drink water because someone (like me) told you to drink plenty of water? Various articles about how much water a person should drink suggest 6 to 8 glasses a day, but for me that's too much, so I think I wind up drinking about 3 or 4 glasses a day. But that does not mean you cannot drink other stuff, too. You drink whatever you want, and just be sure to also add several glasses of water a day as a routine, as a separate habit and in addition to what you usually drink. Drink water, but also drink other stuff, too!
If your need is to stay hydrated, and you don't want to drink tons of water or anything else, then there are plenty of foods that will accomplish that pretty well. Any kind of melon is very watery, like canteloupe, watermelon, strawberries, blueberries. Eating spagetti puts water in your system because when it cooks in a pot of boiling water, it soaks up every bit of that water, great for the digestion. Salads are good also, because lettuce and tomatoes have a lot of water in them. But for gosh sakes, you need to be drinking SOMETHING, and water is fine, and so are a bunch of other fluids and drinks and sodas and tea and just whatever in the world it is you like to drink.
Your friend, GG