Depends a lot on the kind of work you do. If you are roofing in phoenix it is one thing. If you are riding the desk job in an air conditioned office that is another. I have done both so I know you will go through 3-4 gallons anyway when it is stupid hot and you are busting your ass all day. Nowadays I probably only drink 1.5 gallons and I have to force myself to get that much down.