If you live off the grid, that means no plumbing which makes all tubs non-functional.
For children and older this isn’t a huge issue as there are showers that work off the grid. Toddlers and pets are a different issue though. They get dirty but the option on the tub is greyed out.
Although the option on tub is gray, it does still work on the toddler or the adult.
Click with the adult on the toddler and choose Give Bath or click with the toddler on the adult and choose Ask for bath.
Pets work the same way.