Water toxicity

They have said in the past that you should drink so many glasses of water each day, and lately, I have heard that you should drink so much compared to your body weight. This scares me mostly because when your urine turns clear or nearly clear, I assume that this means your body is sufficiently hydrated as they state in the hydration charts you see online. There is such a thing as water toxicity which not only hurts your kidney function, but you could even go so far as to shut them down. One coworker also mentioned that you could over hydrate to the extent that it starts to seperate the walls to your cells and cause untold amounts of damage to the rest of your body. So, how much is too much???