Can the body adapt to dehydration?

Answer 1

Most likely the body won't adapt but if you somehow have something that helps it most definitely can.

The body can adapt short-term to mild dehydration. Moderate dehydration can begin to have deleterious effects after 48 hrs, moderate to moderately severe can be fatal in 7-10 days. Severe dehydration can cause multi-system failure in 24 -72 hrs, depending on your hydration level and general health at the time immediatetly preceding a catastrophic event.