I grew up in Sri Lanka, a tropical country where the days were hot and one perspired a lot. And yet, there was little fear of dehydration. We drank water with meals and the occasional cup of tea but no one carried around bottles of water. Even when my friends and I played cricket all day, we drank when we were thirsty but that was about it. The idea that dehydration was a danger lurking that had to be staved off constantly was foreign to us.
Hence I was surprised when I came to the US, a very temperate climate, and encountered this idea that one should always be drinking fluids. At one time I thought I should drink more water too and started doing so but having to go to the bathroom frequently was annoying and I quickly gave it up. The only fluid I routinely take each day is two cups of coffee and two glasses of water, and drink more only if I feel thirsty.
Adam informs us that this hydration craze is not only unnecessary and could be harmful.