Hamsters need a regular supply of fresh water. You should either provide a water bowl filled with fresh water daily, or you can use a small animal water bottle, available at most pet stores, that will allow you to only have to change the water once a week. If you decide to use a water bottle, be sure the tip is made from metal and not plastic, as your pet will chew through the plastic tip. This could possibly cause flooding in its cage. If you do decide to use a bowl, make sure it's relatively heavy, otherwise you run the risk of having your pet knock its water bowl over, and have no liquids available to him or her.