The rules clearly states that the Bucket is only effective against Pit Water in the Spring and Autumn Waterfall phases.
Thomas, could you please confirm this?
Because the icon on the development tile resemble more the one from the Action Selection Pools (it is exactly the same) rather than the one pictured in Spring and Autumn.
This might lead to think that the Bucket prevents you from receiving any Pit Water also during the taking of the Action Disks from those particular Pools that add Pit Water. This might be also logical since a bucket can always be used to remove water, no matter from it is coming from...
But this, I imagine, would transform the Bucket Development in a too powerful piece of technology for the balancement of the game.
We came across the same question and played it that it only applies to pit water taken in Spring and Autumn. It did not prevent taking a pit water if you took action disks during the first step from the noted action pools. Hope we did that correctly.