https://i.imgur.com/Qe1kPfc.jpeg
Exactly one water tile generated in my world (barely visible in linked screenshot). Only discovered it when I randomly tried to build a pipe there. There's a ton of mods installed so I don't know which is causing it, but it appeared on Rubia so I'm doing my duty and reporting it here as a bug.
No need to worry about balance, it's too small for an offshore pump.
Side note: making iron bacteria an ingredient for biofusion packs was diabolical. Getting nutrients back west around on a 5 minute spoil timer was interesting, but 1 minute bacteria is on a whole other level.