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Comment by nawitus | Hacker News Reader

>"In the future, wars will be fought over water," he says. Two rivers border the land, and the community sits atop 56 known water wells.

This is a meme invented by people who've read about oil wars. The problem is that water is very cheap to produce with electricity. Desalination plants are efficient and the price of water they produce is competitive. In addition, the price of water per kg is extremely low. This means that transporting water over large distances like oil is transported is probably non-profitable. It simply means that it's cheaper (and cheap) to produce drinking water from salt water. There are not many landlocked countries.

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And even if there were land locked countries, natural trade will supply water. When people talk about water wars they envision people dying of thirst, when the reality is that water will go from being fifty cents a thousand litres (!) to a buck fifty a thousand litres and farmers will need to work around it.

Indeed. The first thing that would happen if water were a lot more scarce is that lots of things would become more expensive, since water is an input to just about everything. Presumably people would change their behaviour in lots of ways short of just up and killing each other. "OMG expensive meat!" is a lot more likely than "OMG war!"

Maybe a biased source, but http://www.ecotechwater.com/Company/watertrivia.html:

How much water does it take to produce one ton of steel? 62,600 gallons

How much water must a dairy cow drink to produce one gallon of milk? 4 gallons

How much water is used during the growing/production of a chicken? 400 gallons

How much water is used during the growing/production of almonds? 12 gallons

How much water is used during the growing/production of french fries? 6 gallons

How much water is used during the growing/production of a single orange? 13.8 gallons

How much water is used during the growing/production of a watermelon? 100 gallons

How much water is used during the growing/production of a loaf of bread? 150 gallons

How much water is used during the growing/production of a tomato? 3 gallons

How much water is used during the growing/production of rice? 35 gallons

How much water us used during the production of an egg? 120 gallons

How much water does it take to process a quarter pound of hamburger? Approximately one gallon.

How much water does it take to make four new tires? 2,072 gallons.

How much water is used during the growing/production of a tomato?

I've wondered about the use of hermetically sealed greenhouses where over 95% of the water is recovered with dehumidifiers. The power needed by such dehumidifiers would track solar flux rather closely. Would increases in water costs make such setups economical?

"How much water us used during the production of an egg? 120 gallons"

This is the only one I feel comfortable commenting on specifically, but this is insanely wrong. A laying hen drinks about 16 ounces of water per day, eats a few ounces of food per day, and lays an egg every 1-2 days depending on the breed and the conditions.

Your quoted figure appears to be, quite literally, off by a factor of 1,000.

It does sound a bit high, but to produce a pound of grain it takes about 150 gallons of water, and assuming about 1/2 pound of food eaten every 2 days it is about right.

As the previous poster said, a laying hen eats a couple of ounces a day, no where near a half a pound.

With a cursory google search, 1/4 pound of feed per day seems about typical, assuming 2 days per egg produced.

Maybe, a 'factory' hen that eats nothing but grain might do 1/4 pound of grain. But these hens will also produce very close to 1 egg a day, or about 9 eggs for every 10 days or so.

Also, apparently "rice" is a now a singular specific quantity.

Just curious; I've read that energy takes quite a bit of non-salt water to produce. Energy can be used to create clean water by desalinization, but I believe I read that this still creates less clean water than the clean water needed to produce that energy (though this can be done in a very different area. Would anyone here happen to be familiar with the basic numbers here?

>Desalination plants on average use about 15,000 kilowatt- hours of power for every million gallons of fresh water that’s produced

http://www.bloomberg.com/news/2013-05-01/energy-makes-up-hal...

I'm not familiar with the exact numbers, but I would be extremely surprised if a solar panel or wind turbine took that much fresh water to manufacture and install. I suspect that the argument you're referencing is more likely geared toward fossil fuels.

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