Don't forget to include elevations in your figuring -- you gain app 1/2 a psi per foot of elevation going down hill and lose it going up. for stock watering i usually figure about 5 gpm ( if in doubt figure higher) and look up the friction loss chart for the pipe size and type you are looking at using, you will never be sorry running a size bigger pipe than you think you need. Also don't forget to allow for Fitting losses ( elbows and tees). I would not use less than schedule 40 pipe or pex. go one size larger on the pex to make up for the difference in the insdie diameter. I can run the figures for you or double check your figures if you would like. When reading the friction loss charts make sure that you are reading in psi or feet of head because that will be alot different. 2.31 ft equals 1 psi, 1psi equals .434 ft of head. davem

Lugnut, JT, and Bob= my advice.