At first I thought "Godamn... I wasted too much water from my bucket, it's ****ed." and suddenly I remembered it's metal, metal gets rusty, yeah why not.
When would it lose durability?? After every time it's poured or every time you fill it?? If you've got too many buckets, just throw them away. Don't see the practicality of this one. And if you say 'for realism' that's not exactly valid since you can scoop up lava with it.
It just seems lazy if you want things to eventually break just because you have too much of them. There's nothing to benefit from giving the bucket a durability limit.
I don't like this suggestion. I agree that you should throw them away or make more chests. Lastly, I am already gathering iron, I don't need buckets with durability to make me.
Also encourages more Iron gathering
Also,how many uses would it have?
There is no good or evil, only power, and those too weak to seek it. -The Dark Lord