PatandSue:
They do have bottled water on the ship but you have to buy it. I don't remember how much it is. I have seen people bring their own water on board. Before you try, check the Holland America website. You can even email them and they will tell you for sure.
You are not supposed to bring alcohol on board but I know some people who have. The risk is they confiscate it. You can bring wine and champagne! They have drink cards (alcoholic) but you are limited to certain drinks. We got them one year and some of the servers limited you to certain drinks and some didn't. It is cheaper to go that route but I am not sure how much cheaper.
Hope that helps!
Steph