Don't know where you are located, but keeping the water from freezing could be the bigger issue.

Chickens will go to bed at dark and really don't move until sunrise. As a result, they don't need water at night. I presume ducks are pretty much the same. However, keeping feed and water inside is usually no problem (water needs heating in winter if you want to keep it available at all times-it is only necessary to give them water maybe in the morning and night, then empty the pans after they have a chance to drink so they don't freeze). There are waterers that hold maybe 3 gallons of water in a galvanized can with a moat-like trough around the bottom. The can has a cover that fits down over it all the way to the bottom, forming an airtight seal. At the bottom, there is a valve that opens when you put the lid on and lets water out and air in when the water level drops in the trough. Set it up on cement blocks or something that way so it is several inches off the ground and the birds can then drink out of it, but can't get in and make a mess and the water will stay cleaner if kept up off the floor. There are similar feeders which you can hang from the roof several inches off the floor. Fill the center with food and it will flow slowly into the trough where they can eat. There is a cover for the center so they don't get in there.

The ducks won't be able to wade and swim in the water, but they will have plenty to drink.

I have used the water and feed containers described by beeone. I have a heating cable on the waterer which works well to prevent freezing in all but the coldest stretches of winter, in addition I cut a 24" square hole in the coop floor under the waterer and covered it with 1/4" hardware cloth and any/all spilled water simply falls into the sand below; never any wetting in the coop.

Due to the addition of more hens recently, my coop is getting cramped so I have built a feeder/hopper on the outside of the coop such that I can simply walk up and pour in 50# of feed and close the lid, the chickens feed from a trough inside the coop. Works real slick.

thanks! I've decided to do the "no water at night" plan. when they go in for the evening I'll close them in then let them out in the am. I did this last year and worked out ok,I have a new house for them and I thought that they could be in there for longer periods during the winter and would therefore need water in there too...but if they're going to spend only the nights in there like last year then they really don't need water or feed. I will put a heated water bucket outside the coop during the day for them,should be just fine. So I guess that fixed my dilema!

More to Grow has a great idea with the hardware cloth to let the dirt fall through, and those little heaters work pretty well. When I was a kid, they were the only things that kept the water liquid for more than 10 minutes at 30 below.

My brother's kids had some ducks and they sure like the water. Seemed like they were messier than pigs with a mud hole. The drinking water in open pans always looked like some kind of brown diahrrea. The watering cans can really help keep the water clean for drinking since they can't walk in it. They can get dirt in it, but if it isn't being stirred up, the dirt will settle out fairly quickly.

here the water looks horrible after ten minutes, like it hadn't been cleaned for three weeks. i just gave up since i know it is actually clean and fresh. i figure that's what they do in nature, after all, drink dirt and pond stuff. there doesn't seem to be any health consequence.

ya,ducks are just messy...therefore keeping the water out of their nighttime place will keep things dryer and less likey to become so damp in there.