If you have them in the broode...introduce it. I dipped all my ducks bills in water to show them and pecked at feed with my finger to get them interested. My opinion is the earlier you expose them the better. Yes they can live off their yolk, but I hate to chance dehydration. I also put vitamins and electrolytes with a tsp of sugar the first couple days in the water. But I wouldn't let them swim yet...just make sure they can get their whole bill in the water so they don't get clogged. You can also make a mash of food and water to make it easier to eat.My mallards are a day old, is it too early to introduce them to water and feed?