Is drinking only to Thirst the only way?

Trim....I've heard of Water Poisoning, where someone drinks so much water it harms the Body. But, I believe you would have to willingly do that....like ODing on pills.
I have an alternate approach to 'drinking to thirst'...and that is 'drinking to urination'. As long as I'm going every hour, or so, I figure I'm Hydrated...also, there's a feeling one gets in the Mouth.....WY