Pack the beer in your luggage and it is doubtful that they will say anything. Actually you may be able to get away with it in a carry-on but technically it isn't allowed in most cases. It is the liqour that they mainly frown deeply upon but it is possible that they will 'hold' it for you until the cruise is over. As for the water, the ships water is a pure as any bottled water so it really isn't necessary. If you just feel better then go ahead and bring some with you as it is expensive onboard. What my wife and I do is just carry a bottle or two on with us and when it's empty we just refill it from the tap onboard.