Depending on your conditions, fences, road(s), etc..  You might look into the cheap poly pipe. (NO it is not the regular poly pipe!)  It's used in lower pressure mister situations. 1/2 inch is about .03-.04 cents/foot and comes in 100 foot. The normal poly press in unions will work in the pipe. It is not a good idea to drive over the stuff, but if your situation fits, the pipe could be laid along a fence line, etc..  Probably have to fill the even flow tank the first time, then 1/2 inch should keep up with the needed draw.

 A $150 worth of pipe and fittings would be a lot cheaper in the long run and less hassle than packing 1500 gallons of water a day, for however many days you're going to have the cows there.   

I've done that before to get water to a herd, was only 4-500 feed but worked fine. You do have to keep it away from the animals, they're like little kids,, gotta play/pull/step on/chew everything.

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