The only thing I think of, is you'd be peeing A LOT. Lol
I read recently that drinking a lot of water (3 litre?) every day can really help your skin and general health. Do you think it could, and are there any disadvantages/risks to doing this?
I don't see any real risks there at all as it's actually very good for you. Water keeps your system cleaner of toxins and will help moisturize your skin.
This is absolutely right and very much good effect for your body. Drink water as much as you can....