I agree, it's important to drink more than usual, as you're probably not getting as much liquid from your 'food' as normal, unless you're making them up with lots of water. The important thing is not to dehydrate, but stick to what the booklet recommends. If you drink way too much water, that's not healthy for you either, and can be dangerous if taken to excess. Best to have little and often through the day. And remember, if you're not a big fan of water, you can have things like peppermint tea, coke zero and dr pepper zero for a bit of variety.