The bug
taiga_decoration_1 has trapdoors waterlogged after generation. This results in a massive water mess.
How to reproduce
Load taiga_decoration_1 using a structure block, you'll see the following (everything is included in the F3 screen):
[media]Linked issues
Attachments
Comments 2
Fixed in 19w02a
This was fixed a looooong time ago, I don't even know in which version, resolve as fixed please