Running a hefty modlist of BZ+K2 and tweaking out a good map plus resource distribution for an expensive marathon run and noticed that mineral water has not spawned.

Ran a few generation tests and checked your changelog. Reverted to previous version of RSO and mineral water (and imersite) are spawning again. May want to look into what you tweaked in .23

That will be tricky.
There is literally only bzchlorine added in .23 over .22. It doesn't touch anything related to other mods.
Can you try to produce a debug log?
Extract RSO and in config.lua set debug_enabled to true.
It will produce generation logs in script_output folder in Factorio directory. I could take a look at those to see what's going on potentially.

Im also running a BZ+K2. Been running around for hours. Disabled RSO and mineral water starts spawning(and also imersite)

Can you run it with debug enabled and post log or share the save file so I can sync the mods?
With debug enabled it should print chances for resources at startup.