We have used portable water troughs for the past 5 years, for both cattle and sheep. We have water lines over the whole farm (325 acres) and have risers on these lines, about every 60 or so metres, enabling us to have varying sized grazing areas. We have used poly troughs ranging in size from 1 metre to 6 metres in length, depending on the animals and the number of stock we are supplying.
Having said all of that, this last year, I replaced all of the portable troughs (in most areas anyway) with permanent concrete troughs. The reasons are as follows - now we have one less job to do each move, the cattle can't damage the troughs or break inlet lines, the concrete troughs have a valve called a "Cocky Valve, which is guaranteed not to leak and is virtually unbreakable, and probably most of all, I don't have to have any worrying thoughts that there is a leak and a feeder tank is empty. We can't spare wasting water and each tank is 25000 litres.
Hope this is of interest.