I use a bottle - but it needs to be a good bottle that lets water out easily but also doesn't drip a lot. A lot of people use bowls now but it needs to be really small and shallow - the ikea tealight holders fit that description. I'd suggest using both. He will probably use both. If you use a bowl also, it could do to be on a shelf or platform so it doesn't get bedding in it and get soiled. A corner or one end of a platform is a good place then he's not likely to walk in it. With a bowl, it needs washing out and refilling every day. With a bottle you check it has water in daily and tap your finger on the end of the spout daily to check water is coming out ok and change the water every two days usually.