I'm getting 3 1-day-old chicks on Wednesday. Here's a pic of me getting their water bottle ready
, for the brooder box, and the food container is the same size.
Question - how big a food and water set up will they need in the future coop as adults?
Much bigger! I'd use the two gallon galvanized waterer, and a feeder about that size. There are lots of options, and larger is always better than smaller. I'd also return that cute little thing and get something larger now, so they can't knock it over in two or three weeks. Try the one gallon sized plastic waterer.
Mary
If you can limit it three chickens the same amount will work if you can keep them from knocking it over and you don't let the food or water run out.
You sometimes read on here that all chickens should be able to eat at the same time. With only three yours will be able to do that with what you have. That recommendation comes from the commercial chicken industry where they may have 5,000 hens in one coop. They know exactly how much they want each individual hen to eat for optimum egg laying, but some can be bullies and hog the food. So they wait until all the chickens are hungry and release a carefully pre-measured amount of food into all the feeders. The bullies are too busy eating to harass the other hens so they all get to eat and they only have enough that they can clean it all up. Then, when they are hungry again in a few hours, they release some more feed. With only three bullying should not be a problem for you.
I don't think you need to go as big as Mary suggests for only three chickens but I would also go bigger. There are all kinds of different feeders and waterers on the market or you can make your own. We have different philosophies on how we manage feeding and watering. Some people like to fill up enough to last a week, I like for them to clean the feeder out every couple of days to keep the feed fresher. Personal preference.
How you water makes a difference to me. If the chickens can get to the water and poop in it or scratch trash into it you need to change it every day or two at the most. Also if mosquitoes can get to the water reservoir they will breed in it. Dumping the water and mosquito wigglers every two days will keep them from maturing. Some people really like nipples for watering as they don't have to manage it that often, the chickens cannot foul the water. But in my opinion you should make mosquitoes cannot get to that water reservoir.
The problem with the very small waterers especially is their stability. A standard bird can easily tip them over, soaking bedding, and removing the water that day. You will still want to dump them out every day or so, but not have the birds do it!
Mary
For chicks a small feeder and waterer are just fine, they take up very little space in the brooder.
Once they're older you'd probably want a waterer that holds at least a gallon or two and a feeder that's maybe 5 lbs, 7 lbs or so? Those are on the smaller side which is fine for a small flock, but big enough that you only need to refill once every few days.
I use a 5gallon bucket because they're cheap, easy to install nipples on, and last a long time. I can go on vacation for a week and my helper won't have to refill. I have 8 hens. You could use something smaller if you have a small coop but that bucket is about one square foot of floor space if you're using horizontals. Mine are vertical, they can walk underneath it so it's a zero floorspace situation here.
I used a quart size waterer and feeder in my brooder for my first Flock of 5 and my second Flock of 7.
When I put them in the coop, I use a 2 to 3 gallon waterer and a 12 to 15 pound feeder. .. GC