Some time ago I was thinking about how some water physics could be implemented into VS. In an ideal conditions we should be able to do two major things with water: fill an area (transport canal, irrigation canals, decorative ponds) with water, and drain water from an area that we want to be dry. Here is a crude idea of how it could be done:
Water blocks are not able to create adjacent source blocks if required conditions are not met.
Single water blocks that are required by world gen for waterfalls to exist are also unable to create new water blocks, even if another water block is placed near them, but water from them behaves as normal and lore-friendly explanation to that is: small mountain water source is not enough to fill any reservoirs; water from such source flows for a while and than it soaks into the ground and the rest evaporates)
For water to be able to create adjacent water blocks it has to have large enough volume. It could be determined by dimensions (e.g. 12x12x3) or by block count (e.g. 864 adjacent blocks of water). Also in case of canals: if a body of water, even 1 block wide is long enough that it reaches render distance it would be considered as a body of water capable of creating new adjacent water blocks. Lore-friendly explanation would be: if a body of water is large enough it means that the area surrounding this body of water is collecting enough water during rains that it replenishes any loss of water thus this reservoir can't be drained.
If large enough body of water is opened to new space that it can flood it will do that to a level of highest placed water block in this original body of water (as in communicating vessels principle - you can find it working in Timberborn update 6)
New water blocks can't be created via bucket.
Adding more water from smaller reservoirs to reservoirs carrying large enough volume to be considered infinite won't change their level so player can not overfill an ocean, a sea, or even a lake.
Small reservoirs of water will persist if untouched. Loosing more than 25% of it's original volume (creating more space for this water via digging, or some terrain collapsing) will start a process of slow, but noticeable evaporation.
Only those water blocks that are a part of large bodies of water (and naturally occurring mountain springs) would be considered infinite. From any small reservoir a player would be able to drain water (rule of 25% water loss would be still in place and said reservoir would start so slowly evaporate).
Those points don't cover every situation and are not exploit-proof. But I think that with enough tinkering it could work like that. I know nothing about coding, so I don't even know what is possible with VS game engine and how much manpower would it take to implement water physics into the game.
