Studies show that everyone who has died has had contact with water at least once in their lives.
Actually, water is not the 100% fatal product you imagine it to be. There are infants every year who pass despite never touching water.
Oxygen, on the other hand, that shit's a killer. As a matter of fact, for the DUmmie's safety, I would recommend they abstain from further use of oxygen or water, just to be sure. Once they do that, they won't have anymore problems.