Ok, here goes. First, if you are going to use this to feed cattle, you want to make sure you don't allow the water to stagnate and grow algae, therefore, you will have to install a aeration system inside the tank to insert air, just like you'd do in a fish tank. It should run the perimeter of the tank and infuse air into the water, this will keep down the bacteria and the algae. You can install a pump into the tank that will draw water out of the tank when you turn it on to water the animals of feed the water supply in the barn. If you use a variable speed pump you only need a small booster tank to absorb the shock. You probably need an overflow tube someplace in the tank to set a maximum water level. You will need a lid on the tank to prevent dirt, debris and sunlight from providing nutrients to the water for algae growth. The lid should probably be sealed. In the lid there should be a 2" pipe that comes up from the top of the lid, then turns horizontal, and finally points back down at the lid to allow air flow into the tank. This pipe should have a screen on it to keep out the animals and buggs.

Thats is the basics of a cistern design. If the tank is out of concrete, you may want to seal it on the inside with an epoxy paint to prevent it from cracking and breaking down from water expansion and contraction.

good luck

Raymond VinZant Plumbing Prof.

Thanks Ray. I'm talking with contractors now and will use your suggestions. Since I'm not feeding livestock....just general cleaning.....I'll probably not worry about algae buildup.