I agreebwith whoever said they'd be pissed that somebody just waltz into your horses stall without permission. What if your horse "not that she is" was green? Or fresh? Or didn't like people? Or spooky? And what if she had gotten hurt by your horse? Anyway I thinkmyou do have right to be pissed, but you should also let it go, talk to the woman who took your bucket, maybe she was in a rush and didn't have time to get a new bucket and forgot to text and ask. I'd alsonget a personal water bucket.
Equestrianism; 10% luck, 20% skill, 15% concentrated power of will, 5% pleasure, 50% pain and 100% reason to remember you're absolutely insane to be riding a beast that big.