We usually get about 2 weeks in January or February where it gets down below freezing every night and doesn't warm up enough during the day to thaw it much. Where I used to live, I only had a 250 hose to get water to the trough, and even though I swore I was going to disconnect all the pieces and walk the water out of the hose every time, I would invariably forget one time and then I was done for. I had to haul water to the trough two 5-gallon buckets full at the time. 4 horses can drink LOTS of water it 2 weeks, and like you say, it got REALLY old after a while. Plus, last year when Bob was a baby, he coliced and the vet said he probably wasn't drinking enough water, because the water was so cold. So I thought a heater might be a good investment.
Oh yeah! I know! We shove the hose under the house and it won't freeze that way, if we remember.