OK you chicken nipple users. Let me know how those work out for you. I bought some but never used them.
OK, here is a detailed account of my experience with these things...
when my chicks hatched, I started them on the waterer by putting a nipple into the cap of a gatorade bottle and hanging it upsidedown. They pecked at it but over all seemed disinterested. After a few days I figured it out. The darn things don't work in a vacuum. They will dispense a little water until there is a vacuum and then they quit because they don't allow enough air to go in via the nipple. I cut a small hole in the bottom of the bottle (which made it tricky to fill) and after that it worked great and they took to it right away. With 15 of them though, I was having to fill it like twice a day. So I bought a 96 oz bottle of juice, enjoyed the juice, and then converted that by again installing a nipple in the cap. This time I cut a large hole in the top so I could refill it easily with a pitcher from the top without taking it out or anything.
That's where the trouble started. A few days later, I noticed the chicks were constantly pecking the waterer. Constantly. I checked it, and water wasn't coming out. I removed it for investigation and found that the little stick part that is on the inside (inside the plastic shell they have a stick, a ball, then another sitck that the chickens peck at) was stuck. This didn't allow for any water to get through. I cleaned it out and put it back and it was fine for maybe 2 days and then it happened again. I noticed the water level wasn't going down like it should so I checked and again the little stick was jammed. There was no debris that I could see so I figured there must be chicken dust getting in through the filling hole on the bottle (I had cut almost the whole bottom out to make it easy) and settling at the bottom and even though I couldn't see it, it was just enough to mess up my waterer. While they were in the garage, I had to clean it carefully every couple of days.
When I moved them outside, I took one of my many, MANY buckets I have laying around because my aquarium salt comes in them and drilled 2 holes in it and installed 2 nipples, in case one gets jammed. With only 4-6 chickens one would have been enough but I am hoping if one jams the other will still work until I either notice or clean it out. I have the lid on it to keep debris from getting in with just a tiny slit unsealed to allow air in to avoid a vacuum. I have not had them clog yet, but every 5 days or so I rinse it out really good and refill it. I have not had a problem since I did the bucket version. The lid part is key. You need to be able to keep dust and dirt out in my experience.
I have figured out how to tell by watching the chickens as they are drinking, whether or not they are getting water. They make a little um...lip smacking (if chickens had lips...) motion after every couple of pecks if water is flowing. So far so good. Like I said, avoiding getting any dust in there is really the key I have found. I LOVE not having to deal with poopy water.