So we could do games like Gish or just get (semi) realistic water.
Download Rigs of Rods.
Look at how many bugs it has.
Re-consider if you want softbody physics. 
You can simulate water pretty accurately just by slowing stuff down that is in it. You can even give any tile with water on a depth and relate the speed of an object moving through it to the depth, even drowning objects that get to close. You can use animations at the edge to make some (semi-realistic depending on how skilled you are) waves.
There’s difference: Rigs of Rods is 3D game, I’m talking about 2D softbodies, like in Gish.
2D softbodies are easier to implement and there are also already made libraries for such. Go play (or watch videos of) Gish if you want an example. Main character is softbody.
Also authors of RoR are working on better version of it from scratch, unfortunately it’s paid one this time (forgot name, sorry, but it was on Lazy Game Reviews YT channel).