The SnapLock Formex is a serious best cheap coop, but it is built to house a large flock for a long time. If you’re serious about raising chickens, this is the prosumer poultry palace for you.
I have the possibility of incorporating rain water collection, but obviously that’s limited to warmer temperatures. Same with dragging a hose out there. So hauling water to the coop will be a reality in the winter. I do have the option of getting power to the coop. I use deep litter and if at all possible would like to keep the water off the ground – though I know that adds an extra complication and may not be possible!
For 12 chickens I use a 10 gallon semi clear plastic tote, horizontal nipples, and a stock tank deicer that is rated for use in plastic containers. That lasts me over a week. It has stayed thawed to -22 degrees F. That is -30 C. However, at -22 I noticed frost forming on the top so I’m sure if it were colder the water would have frozen. Have considered adding insulation to the totes if a problem happens. This system could be used with rain during the warmer months.
For your 25-50 chickens you could try a larger tote or 2 or more waterers, depending on how much electricity you have available. You’d have to fill them more often than I do. I’m fortunate as there is a faucet in the well house and I use that with one of those 100 foot shrinking hoses. I think I remember someone using a larger barrel with the horizontal nipples and deicer. That might work better for your circumstances.