Tuesday, April 1, 2008

Water 101: what is the water problem?

source: http://www.flickr.com/photos/anatomist/221165572/sizes/m/

Right, its about time I get into the meat of technology. My specialties are water, sanitation, and energy. This doesn't mean that I know everything about it, but if you put anything to do with these things in front of me, I'd likely figure it out and understand it fairly quickly. So if you have questions about these, ASK!!

I'm going to start with water technologies. But before we get into the technology, its important that you understand the water problem.

A common question that I'm asked by people is...there's so much water everywhere...how can people just not have access??
So here's your answer:

1. Well, you are right...there's a lot of water on this earth...about 326,000,000,000,000,000,000 gallons (326 million trillion gallons) of the stuff (roughly 1,260,000,000,000,000,000,000 liters). Considering that there are 6.6 billion people, that's like 49 billion gallons of water per person.

2. But most of it is NOT drinkable (also known as non-potable):

percentage of usable water (source: USGS)

water distribution by percentage (source: USGS)

Estimates by geologists and other scientists state that 97-99% (see above pictures) of all that water is stored in the oceans. Oceans have very salty water, which cannot be used for drinking, washing clothes, cooking or for dishes. You can't use it for cleaning either, because the high salt content can corrode or adversely react with many materials (which is why most things dumped into the ocean decay rather quickly than on land). Of that 1-3%, over half is hanging out in the North and South poles in the form of ice-caps and glaciers. The leftover is in the form of lakes, swamps, and groundwater. I'd probably say that's the percentage that's eligible for drinking (with a caveat, see point 3). So now, the water count is more like 158 million gallons of water per person (for your entire life). Assuming you live for 67 years (which is the current life expectancy of an average person in the world), that means you have 6500 gallons a day. Now you might think that's a lot, but its not really...because...

3. Most of the part that's drinkable has issues of pollution, accessibility or availability:

projected annual water available per capita by geography in 2025
source: Water Resources Institute, Page 200

Availability?? YES! Firstly most of this water is not yours. We haven't accounted for the animals or plants or the rest of the ecosystem that share this earth with you (and frankly, outnumber you by a large margin). So that itself, takes the per person amount significantly. Plus the water is often not anywhere near you. Water usually concentrates itself in specific areas, not equally across the land surface. And generally large amounts of water are in places that people proportionately don't live in or near - like forests, rivers, and large lakes. Which means that the water needs to be piped over to you. But if you are in a poor country and don't have the means to pay for a pipe, chances are you won't get any water. And you have to walk miles to fill up a pot of dirty water. Add on top of that the pollution of the few water sources we do have - natural and man-made - and that decreases the accessibility even more. This is how over 1 billion people in the world have NO access to freshwater. So really, there's a shortage of fresh drinking water on the planet!!

(source: http://holamun2.com/wp-content/uploads/2007/08/dirty-water.jpg
source: http://www.flickr.com/photos/beija-flor/)

So this is what we are trying to address in the water technology parts - technology that improves accessibility and/or reduces pollution, particularly for the poorer people that have no access.

Please note:
1 gallon = 4.78 liters
1 billion = 10^9 (the US definition)
1 million = 10^6

More information:
United States Geological Survey site for water: http://ga.water.usgs.gov/edu/
The Pacific Institute's Water Think Tank: http://www.worldwater.org/

WHO Water Page: http://www.who.int/topics/water/en/
World Bank Wat/San page: http://go.worldbank.org/PRR44UVHT0
How Stuff Works on water: http://science.howstuffworks.com/h2o.htm
The World Resources Institute: http://www.wri.org/

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