Hello and Welcome to BYC. Glad that you have joined this poultry loving community. I do hope you find a way to keep their water clean. When you do please share it here with the rest of us. I'd like a few ducks myself. Muscovy ducks are what I would like with my chickens. White ones.
A wire mesh, plastic coated 1/2" holes on top of a platform maybe 4' x 4' use galvanized sheet about 24" high to surround it. A hot water heater pan ( Lowe's) can catch the drippings. set your waterer in the center on top of the wire. you can improvise on the dimensions. welcome to BYC! I hope this helps.