The little boy I used to nanny for was like this.
I would put his milk in a sippy cup or in the bottle and he would hold it, that was the only way to get him to drink anything. Besides his mom's breast!
Sometimes he would not do it, so through out the day I would just give him little sips of water, milk and juice. He would take a few sips about every 30 minutes or so. We tried to get him hungry so he would take a whole bottle, but it really was just not working. This was the only way he would intake any kind of fluids.
Good luck!