Same here, except I use the black river "tubs" sold for livestock. They are more durable than hard plastic and you can"pop" ice or by flexing them or just dropping them on the ground since they don't break.
Just a thought, but if you are going to bring water in overnight, bring the food in too. Unless you are feeding fermented food, your chickens have to expend a fair amount of energy to digest dry food. To do that, they need water. So, if no water, dry food is costing them nearly as much energy as they're getting out of it...and costing you a lot for nothing. Remember, they only really need water after eating dry food, so if you can tend them the water doesn't need to be out that long.