You rarely see people out and about on walks unless they’re clutching a bottle of water, (or carton of coffee).
There is no medical evidence for the fashion for drinking extra fluid. Our bodies are generally self regulating (homeostatic) unless we are ill, and we know when we need to drink because we will be thirsty if we don’t.
Sometimes as people age they need to be reminded to drink enough fluid, of whatever sort, because their systems are not so efficient, similarly young children.
Water has no magical properties of detoxifying, healthy kidneys do a good job of that, as others have sensibly posted.
Urine colour as MoMB is a good guide.