True, nukes have fresh water available. (Yes, I was a navy nuke officer.)
No, they never have enough fresh water for comfort, not enough for good showers, and absolutely not enough to use it flushing the toilets.
A friend worked in the engine room on a 70s missile cruiser off of Vietnam. Fresh water was at a premium but as an engine room guy they had dibs on fresh hot water and would shower In The engine room (or vicinity), at the end of their shift.....even when it was restricted to the rest of the crew.
That reminds me. My wife’s nephew is a nuclear engineer and a newly minted ensign on a sub somewhere. Next time I see him I’ll ask him the current state of ‘turlits’.