dpb wrote:

Well, they'll reach as far as they can if thirsty, just like they reach
under a fence for that delectable blade of grass...

About 3-ft is probably practical limit--but you have to count for the
water level dropping as they slurp it down, too. Even in cold weather
they'll average 3-5 gal/day/head. So far all we've used are the round
metal tanks--typically 12-ft diam are convenient to handle/haul and one
or two are enough for each location.

Ok, 12-feet it is. How tall are the tanks, and to how far from the top
do you fill 'em? Next time you're out, please take a tape rule and your
digital camera. I've already started on drawings, but have /zip/
experience with cattle operations.

Not sure the best estimates for weather to try to use as I think of this
more. The problem as I see it on further consideration is that the
coldest weather is when the pita factor kicks in the most as that's when
if the heaters go out the tanks freeze fastest and thickest so both
longer time w/o water and more waste and more trouble. Yet to design
for the 0F/30-mph condition would probably be way over what could be
practical. I'll have to think some more, Morris and take this offline...

I have historical weather data from NREL (National Renewable Energy
Labs, www.nrel.gov), but need to know more about less scientific stuff
like portability and what would make for ease of deployment and how to
build something that won't be done in by curious/bored critters.

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/