8
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So today I was challenged by my Uncle because he says that we are going to run out of drinkable water on earth before we run out of Oil, I told him that he is just saying that to scare me but he honestly thinks that this is true. So I wanted to do the math for him to prove that we have nothing to worry about. But I got a lot of it finished but I have hit a brick wall, I do not think my math is correct so I would like you guys to help me prove that my math is correct.

My variables:

Volume of Earth in Cubic meters: 260,000,000,000 cubic miles
Volume of (any) water on Earth: 75% of earth's volume, 260,000,000,000 * 0.75 = 195,000,000,000 cubic miles
Volume of drinkable water on earth: 1% of Water, 195,000,000,000 * 0.01 = 1,950,000,000 cubic miles
Conversion of Cubic Miles to Gallons: 1 Cubic Mile = 1.101117147e+12
Gallons of Drinkable water on Earth: 2.147178437e+21
Conversion of Gallons to Ounces: 1 Gallon = 128 Ounces, Total of 5.359357378752e+32 Ounces
Average person consumes: 64 Ounces of Drinking Water per day
People on earth: 6.5 Billion
Average amount of ounces each person drinks of water per day: 64 * 6,500,000,000 = 416,000,000,000 Ounces of Drinking Water per day for every person on earth
How many days earth drinking water would last with this amount: 5.359357378752e+32 / 416,000,000,000 = 1288307062200000000000

I just want some math people to check my work. I am only 15 trying to debate with a 40yo haha, I do not want to screw up.

Thanks for any help and it is well appreciated!

  • 3
    Water is recyclable. Oil is not. Burning petrol/gas produces water, etc etc...2011-02-05
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    This is not a mathematical qn, but you should do some more research on this. This is to get you started: according to one official estimate, it takes 2,400 gallons of water to produce 1 pound of meat. Not all of it is drinking water, but a lot of it is. What you drink is a tiny fraction of the drinking water that you consume. @Moron While water is recyclable, some ecologists say that the whole system only works while the percentage of water in circulation compared to the water available does not exceed a certain threshold. What that threshold is and what happens when it's exceeded - who knows.2011-02-05
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    Don't forget rainfall! Or [XKCD people changing stuff with butterflies](http://xkcd.com/378/).2011-02-05
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    Earth is 75% water by volume???2011-02-05
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    Your uncle has a good point. Water scarceness is *already* a major problem for many countries, and bound to become much more problematic and expanded in the near future. Few regions in the wold (e.g. central Europe) don’t have water problems … all others have or will have soon. But kudos for making the effort to reason rationally about the issue.2011-02-05
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    After some deliberation (and a meta thread at http://meta.math.stackexchange.com/questions/1597/how-many-gallons-of-water-is-on-earth-to-this-day ), I have decided to close the question. There are too many non-mathematical problems with what you're trying to do to make this on-topic.2011-02-05

3 Answers 3