Hi folks,
I did some testing with water and I want to share some of my thoughts.
I created some lakes and with only 1 wetsone I was able to fill my lake easily.
When creating my first river, I saw that my lake drain and only 1 mm of water remains in the lake and a water fall is created on the edge of the cliff.
I understant the physic that allow only 1 mm of water before falling to next level, but it is not really pretty…
Also if you create a second exit for the water, it doesnt split, the one nearest the wetstone will flow the other will be dry or mostly dry (not flowing). I had to add more wetstone to get it flowing.
After I decided to create a hole in my lake to have an underground river. Again before it exit the cliff, it was fill 100%, but when a hole appears in the cliff, it drains to 1mm…
To have good looking river, I had to build walls just by the cliff and only allow the last block to flow downhill.
I attach a screenshot showing my lakes and rivers.
What do you think ?
Oh I forgot, the map lake (from the world generation) seems to be filled by this new water, I almost flood the rest of the map while doing this 
don’t forget to add drystone !
And my CPU was all used by LUA (88%) also during the experiment.
Hope this help !