Clinically speaking, water is far more dangerous, as you can drink enough to poison yourself to death.
;-\
You are truly lost.
No one ever died of a marijuana overdose, but that’s not the only way to be harmful. It impares your judgement, which is why you can’t do the same sort of things you can’t do while drunk on it. It also damages the lungs in a manner similar to other kinds of smoking, although the overall effect is milder than cigarettes, for instance, because you don’t smoke as many of them.