Thanks for all the rec's guys. My longest run will be around 4000', but there will be multiple watering stations off of it, potentially watering two different groups at a time, with tanks not so big that i could get away with 3/4". (some of the tanks will be portable, some permanent) I"ve done the math on my pumping unit and gallons per minute requirements for the herd size, which is why I know i'll need to start the longest run at 2.5". (I did the calculations for PVC...not sure if HDPE has a different flow rating, probably does.) I was concerned with pricing, labor costs, and repair issues. I was talked into using thin wall PVC for a previous project by a contractor i hired and it has been a nightmare. Lesson learned. Can the HDPE be put down with a shank type machine, or will i still need to dig a trench? I've never heard of gasketed PVC. The link to the 2" HDPE was twice as expensive as my price for PVC. So, I'm not sure that is feasible. I believe i was quoted around $.87/ft for 2"...unfortunately 2.5" was around $1.20/ft, if memory serves.