I have 4 small ducks with my hens. Last summer, the ducks had a concrete mixing tub (pic attached) that I picked up at Home Depot. It was pretty easy to clean. Emptied old water into a 5-gallon bucket, and refreshed it every day. This winter, I'm using a black rubber feed tub that I bought at a local feed/grain, etc. store. Maybe 3-gallon size, so it's easy to give the ducks fresh water every day. Either way, both are easy to maintain and get fresh water every day.