how to disable using buckets in certain regions to pickup water

[royal sierra]

So, I want to disable buckets from picking up water in certain regions even if the player is not standing in the region that the water is in.

[finite siren]

i would check if the water that is getting picked up is in the region

[frosty marlin]

on player filling a bucket:
  if "%region at player%" doesn't contain "your region":
    cancel event if event-block is air