I sure hate having to do that. I used to have to do it at least once a winter where I used to live because the only water I had for the horses came from a hose run across the yard to the trough at the fence. I always tried to remember to drain the water out of it each time but I would invariably forget one time and it would freeze. On those days that it didn't get above freezing during the day and thaw it out I had to haul water to the trough in 5 gallon buckets. I used to just lug them out there by hand but two of those darned things weigh about 100 lbs, so I got me a little red wagon and started pulling them out there in that. It helped alot! I don't have to worry about it now. The mares at my MIL's place have a running creek to drink from and my BIL has one of those self-draining spigots that shuts off below the freeze line for the trough at his place. Now I just have to break the ice on it with a crowbar if it gets too thick. Much better situation.
On those cold mornings, we like to make our horses a hot mash, by pouring hot steaming water in their grain. If you pour it in the house, it usually cools enough by the time you get to the barn that it won't burn them. They sure like it when it's cold and frigid out :~D