Too much water will kill you eventually. Funnily enough, we know how much water it takes to kill you, but we haven't discovered that limit on cannabis yet... but there surely is one.

In any case, the question isn't so much how it affects you while it's active, but how it affects you long-term. Transitory effects of any nature are not a concern, unless we're talking about rage fits or other behavioral changes that are actively and directly harmful to others.