They are wonderful. I made mine with an automatic lawn watering valve ($24 at Lowes) which screws onto the faucet. It is programmable so you can set it to run for x amount of time x amount of times per day, week, every other day etc. I attach a 100 ft water hose that runs to the pens. I use a washing machine hose to connect the hose to the pvc pipe system I built. The pvc lines are on the inside wall of my pole barn and run 6 1/2 feet off the ground. i use t's every where I drop a line to a waterer with a ball valve on each drop to control water flow. The valves are a must if you are running to multiple pens or you will have all your water running into 1 pen. I am currently running water for 10 minutes twice a day to the dog kennel, the pen the ducks stay in at night and 2 turkey pens. The watering valve runs off 2 AA batteries and has been running for nearly two months now and still no low battery indicator light on. I'm in heaven.
i have two labs in the kennel so I have a rubber horse bucket (chew proof) sitting in a kiddie pool. The bucket stays full of fresh water and the overflow keeps the pool full which the labs love. The duck pen also contains a kiddie pool which is always full and gives the ducks a place to splash and play at night while they are penned.
I set up the Little Giant Automatic Waterer (~ $25 from Amazon.com) a few months ago, and I like it so far. I don't have a water source at their shed, so we built a "water tower" ( $10 for food grade barrel, free scrap wood and copper pipe, and about $20 in plumbing supplies from Lowes). I only fill it about 1/3 full and it lasts for 2-3 weeks for 6 runners. I do dump the dirty water in the bowl every morning because they free range during the day. Even though I make them rinse off in the kiddie pool before bed, they still save some dirt in their bills to put in the waterer.
They were caged for 3 days while we were away and the waterer stayed nice and clean! The bowl comes off easily and the valve keeps water from coming out while the bowl is removed. It did take a bit of adjusting to get the valve right when I first set it up. The instructions are minimal, and it kept overflowing. Now that it is adjusted, it is very easy to maintain.
I have purchased the king size bowl since the pic was taken. It allows them more room to submerse their bills.