
Making Ocean Water Drinkable - prawn
http://www.popularmechanics.com/technology/infrastructure/a17040/how-it-works-desalinating-ocean-water/
======
aaronmoodie
It's disappointing that desalinization has taken precedent over recycling
water. There have been many developments in this area –including the one Bill
Gates has been supporting [1] – yet despite being the more cost effective
option, people can't get over the idea of drinking water that was poop.

[1] [http://www.gatesnotes.com/Development/Omniprocessor-From-
Poo...](http://www.gatesnotes.com/Development/Omniprocessor-From-Poop-to-
Potable)

~~~
mapt
I'm a bit anxious about sewage to drinking water efforts.

While I'm fairly confident that we can eliminate most live pathogenic
organisms from sewage with enough work, excreted toxins, hormones, and
undigested pharmaceuticals are another matter. Diluting those through a
watershed serves a real purpose that sewage treatment facilities are not up to
replicating.

~~~
RodrigoT
What about a grey water system? neither your toilet nor your lawn needs human
consumption grade water.

~~~
gambiting
Wouldn't it be an absolutely huge cost to lay down another set of pipes for
non-human drinkable water? Especially in cities.

~~~
eterm
Non-potable is the industry term for "non-human drinkable".

And yes, the cost of that would be huge, not just in cities. In the UK the
decision the victorians made to not have separate sewage and rain water
drainage systems still has a knock-on today and costs a vast amount in water
treatment, but the cost of separating rain runoff and sewage is still seen as
prohibitive.

edit:

However, on a small local-scale grey water systems can do a lot of good, both
for re-use but also rain water capture and re-use would help with flood
prevention. If houses captured rainwater for use for lawn watering and other
appropriate uses, this is something that could be done without great expense.

~~~
kwhitefoot
Be careful of the law of unintended consequences. Rainwater capture will be
fine so long as only a minority do it (how small I don't know) or only a
fraction is captured but if everyone does it then it will change the economics
of water supply and give people incentives to use the captured water for other
than lawn watering. For instance they might use it for flushing toilets or
even bathing. the problem that then happens is that the local water table will
fall because it is not getting the water that it used to because that water is
now flushed into the sewage system.

I'm not arguing against the idea, especially as it is typically implemented in
the UK where a house will generally only have about 500 litres of storage, but
scaling it up and making it a requirement could cause some interesting
problems.

~~~
lsaferite
Some US states have laws preventing rainwater capture. Water rights being a
weird and complicated thing.

------
1971genocide
Having lived in the Gulf Countries - I feel that they were ahead of the curve
for some time when it came to water.

When I lived in Dubai water was really expensive compared to the UK.

You also never drank from the tap but bottled water.

Even the culture adopted to it where people would think you were super posh if
you took showers longer than 10 minutes.

Also they has some interesting techniques for desalination. For example I used
to live near an aluminium smelter.

Apparently the heat generated due to smelting was recycled to desalinate sea
water to produce water and was sold to consumers.

------
rjv
So this process re-introduces the brine back into the ocean, in turn making
the ocean water more salty. What type of ecological ramifications does this
have on the wildlife in that area?

~~~
elektromekatron
The volume of water being drawn from and the volume of evaporation,
precipitation and runoff affecting that body of water, dwarf this desalination
plant by an exceedingly long way.

~~~
mikeyouse
It's not the overall volume of slightly saltier water, it's the hot,
concentrated brine that's damaging. Most systems are designed today such that
the brine is _only_ ~50% more salty than incoming water and _only_ a few
degrees warmer, but it's still a significant ecological issue.

------
timonoko
Why do they move large amount of salt water when they could move only the
sweet water? When the plant is 100 meter down, the water pressure is already
the required 10 atmospheres, and when it is offshore at an ocean current the
saltifying effect is a not problem. The energy needed is basically the same,
but there is much less friction in the pipelines when you move only the non-
pressurized end product. In my hand-cranked reverse osmosis plant the
difference is 100-fold and you get good 30 minutes exercise for a cup of
drinking water. If you live in a submarine, you could just turn the tap and
the clean water flows in without any cranking.

------
AdmiralAsshat
Just glancing at the article, it struck me how similar this picture from the
article is:
[http://pop.h-cdn.co/assets/15/35/1440426015-desalinization-2...](http://pop.h-cdn.co/assets/15/35/1440426015-desalinization-2.jpg)

To an 1880's Ogden cigarettes card demonstrating how to make an emergency
filter inside of a bucket:
[http://digitalcollections.nypl.org/items/510d47da-d09a-a3d9-...](http://digitalcollections.nypl.org/items/510d47da-d09a-a3d9-e040-e00a18064a99)

150 years later, and the method is pretty much identical.

------
jimiray
Or we could just stop wasting water on Factory Agriculture of Animals.

[http://www.cowspiracy.com/infographic/](http://www.cowspiracy.com/infographic/)

------
zer00eyz
The fact that we CAN do this is impressive.

Should we do it is another question. This is one of a host of technologies
were going to have to adapt to keep the water flowing not only here in the
states but across the globe. Storage, recycling, improved transit (most water
systems loose 10%-30% in transport due to aging infrastructure). The reality
is this is one part of a systematic change were going to have to make to keep
things going.

------
xutopia
This scares me to no end. I see a future where all our water comes from
bottles and we have to pay for the right to drink.

~~~
viggity
It is kind of the natural conclusion when you decide to build a metropolis in
a desert.

Come to Iowa, our weather isn't as nice, but we've got a shit ton of water.

~~~
e40
Really?

[http://www.desmoinesregister.com/story/opinion/columnists/io...](http://www.desmoinesregister.com/story/opinion/columnists/iowa-
view/2015/08/24/water-works-nitrate-farm-bureau-discussion-stowe/32268923/)

Aquifers aren't infinite.

------
ssaddi
Very interesting article ... namely because fresh drinking water is now
becoming a valuable resource. I'm sure the time the article has been written,
better and more efficient ways would turn up for churning out fresh water for
public consumption.

~~~
soft_dev_person
I feel a very American point of view in your comment. Hasn't fresh drinking
water been a valuable resource in plenty of places in the world for as long as
time can remember?

~~~
TheSpiceIsLife
Two years ago I moved from South Australia to Tasmania. South Australia is
known as "driest state in the driest inhabited continent in the world"[1].
Here in Tasmania there's water oozing out of the side of the hills, I'm still
amazed by it.

1\. [http://guides.slsa.sa.gov.au/water](http://guides.slsa.sa.gov.au/water)

Someone else has usually put it better, this time I'll draw on user adrusi:

___________

[https://news.ycombinator.com/item?id=8995524](https://news.ycombinator.com/item?id=8995524)

The problem with freshwater is not that the global supply is limited, rather
that supplies in some high-population areas are.

The Amazon river sends 209,000 cubic meters into the Atlantic every second[1].
That's 18,100,000,000 per day. A single human drinks about two liters (0.02
cubic meters) every day. There are 7 billion humans, so the global requirement
is 140,000,000 cubic meters of water. The Amazon alone contains 130 times more
than the global requirement for drinking water.

This is domestic consumption, which comprises 10% of water usage[2]. That
means that 13 times more water flows through the Amazon than all of humanity
uses. That's just one river. [1]:
[https://en.wikipedia.org/wiki/Amazon_River](https://en.wikipedia.org/wiki/Amazon_River)

[2]: [http://www.lenntech.com/water-food-
agriculture.htm](http://www.lenntech.com/water-food-agriculture.htm)

___________

~~~
soft_dev_person
Clearly. I was just considering the drought in the west of US lately and the
statement "is now becoming".

Personally I live in Norway where we wash our garbage and shower in high
quality drinking water. I still find it absurd from time to time, considering
the lack of fresh water in many places in the world.

Edit: Corrected quote

~~~
Swizec
We've got a similar situation going on in Slovenia. I don't know if we have
more fresh water than Norway, or not, but there are towns that get 3meters of
rainfall per year.

One such town has an area of 25km^2, that's 25,000,000 square meters. Which
means that on an average year, 75,000,000 cubic meters of fresh drinkable
water fall from the sky.

Comparing that to stats in the grandparent post: _14 times_ as much drinking
water falls on a tiny town in a tiny European country, as the whole world
needs for drinking.

That's crazy.

~~~
computator
Somewhere in your calculation there's an error.

75,000,000 cubic meters of fresh drinkable water fall from the sky _per year_
divided by ( 0.002 cubic meters of drinking water needed per person _per day_
x 365 days in a year ) = 103,000,000 people quenched per year.

Your tiny town gets enough fresh water from the sky for 103 million people --
still impressive.

