If you are worried about your baby spilling water everywhere, try the Heinze non spill cups. They have a small one that holds about 120mls and is for babies from 4 months of age, and a larger one that holds 280mls for babies from 9 months of age. My almost 9 month old son has been drinking water or juice out the smaller one since he was 4 months old, and now drinks his milk out the larger one. They have a special non spill lid which is great as nothing comes out when tipped upside down or shaken. And as they still have to suck to get the fluid out, it is suitable for any age. My son went straight from the breast to these cups and has never had a bottle. They are a little pricy (about $8 for the smaller one, and $13 for the larger one), but are well worth the money, and last well. I highly recommend them.
Mother of 3, Qld