In the medieval era alcoholic drinks were widely consumed because the available water was usually not safe to drink. This was especially a problem in the relatively crowded urban areas where the fresh water supply was contaminated with human and animal waste. In North Europe people may have consumed as much as a gallon of beer per day. Wine was also very popular but for the most part it was dilluted heavily with water. At this time chlorine or iodine treatment was not available so we need to keep this in a proper perspective.

If any of you are interested, here is a link to a well researched scientific review of some "common knowledge" regarding water consumption.

http://dms.dartmouth.edu/news/2002_h2/pdf/8x8.pdf

yes water

Just because you drink over 1 gallon a day now does not mean you will not survive on less for a very long period of time

I think the reason not many suggest 5 gallons per-person per-day is they don't want to overwhelm people and make them think it's not possible to be prepared.

Personally I live near a Lake and multiple rivers (within 5 minute walk) so water is my LEAST concern. I do however get 5gallon jugs delivered weekly so I've always got atleast 15 or 20 gallons on hand.

I gather 1 US ounce is 29.57ml, so 139 ounces is about 4.1 litres a day.

That sounds like a lot to me. I drink about 1.5 litres a day. None of that is water; it's either coffee, milk or a blackcurrent drink.

I do wonder whether you are, indeed, addicted to tea and coke and whether it's the addiction which is causing you to drink so much. Which isn't to say tea or coke are not good sources of water, just that they may be causing you to drink more than you need.

I'd add that diet can make a big difference too. Junk fast food and ready-meals can have bad stuff in it, but so can posh restaurant food. The restaurant people mainly care about it tasting good so they put in loads of fat and salt. If you prepare your own food from fresh ingredients you know what you are getting.

For example, last night I had a microwave pizza, and I also had a litre of pineapple juice with it. That meal caused me to roughly double my fluid intake for the day, to deal with it. I drink more after Chinese food, too. If you habitually eat out or eat ready-meals, that can contribute to your needing to drink a lot.

I drink almost no sodas, and drink either water or milk with meals, or the occasional glass of wine/beer. I have no desire to dress up my water with anything. I like water, and have never gotten bored with the taste. I also live within 2 miles of an artesian spring with the best tasting water I've ever had. Costs a dime a gallon, and my wife and I usually have about 35 gal on for drinking only. we fill up other containers with tap water for bathing, cooking, washing, etc. and keep about 40 gal on hand for that, not to mention the hot water tank, bath tubs, and sinks that we'd fill up if we needed to.

I think a better more accurate estimate could be inferred thru water needs when backpacking.
In my experience backpacking when you must provide water for all your needs including re-hydrating food then 3 gal per day minimum is a better estimate,and this only allows for minimal clean-up. My wife sends me straight to the shower when I get home.
The military allows something like 5 gal per day when you are working in a hot dry environment.

That's a great point. If I happen to grab a cheeseburger and salty fries for lunch one day I'll notice I am much thirstier.

I think a lot of people (myself included) are probably walking around every day in a state of dehydration. I've tried to get away from soda whenever possible and substitute iced tea, juice, Gatorade, or water. Aside from a cup or two of coffee in the morning. Can't go without that!

Actually, it's not necessary to keep your urine crystal clear. The color will vary with the volume of urine. You could be normally hydrated and still have colored urine if the volume is not that large. Sure, if you drink more water than your body actually needs, urine volume goes way up and your urine will appear clear, but in that case, you're wasting precious water. That's fine in every day life, and probably a healthy habit, but a waste when water is scarce. Oh, and of course, diuretics can increase urine volume, resulting in clear urine, but it's actually dehydrating you. Actually, I find that very cold weather also acts as a diuretic for me (it's called thermal diuresis) which can result in clear urine even though I'm not drinking any extra fluids.

The opposite would be a more accurate indicator. If the color is dark, then I would think about drinking more, although that still isn't necessarily dehydration. And various medications can cause dark urine regardless of hydration state, so that's something to be aware of.

Personally, I think the best indicators would be to gauge how you feel and also to weigh yourself. If you're losing weight during the day, then you're becoming dehydrated, particularly if you're experiencing the typical symptoms like headaches and cramping. Of course, high temperatures, low humidity, heavy exertion and other factors may require you to drink more to stay ahead of the dedration curve, so to speak, but for normal folk, weighing yourself will work. Actually, I'm curious if those members who are drinking like a couple gallons per day, if they are consistently gaining weight over the course of each day versus their morning weight. If not, then that's quite a high water requirement that surprises me, for non-athletes.

That said, I'm glad you mentioned the danger of too MUCH water. More of an issue for athletes, generally, but an important point. I made a long post about that a while ago, if anyone's interested in reading more on that topic and how "common wisdom" has changed over the years.