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Comment by nojvek | Hacker News Reader

Same H2O molecules, different levels of other molecules mixed in with it.

It is possible to recycle urine into drinkable water. That’s what they do in international space station where water is very precious.

https://www.nasa.gov/mission_pages/station/research/news/wat...

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They also do it in Singapore iirc.

I'm curious why this would be worthwhile: since Singapore is an island conventional desalination would seem easier than either coping with the witches' brew of sewage (random amounts of random chemicals) or the expense of plumbing urine separately.

Seem being the key word here; if it's plain sewage, there's affordable, scalable and relatively low energy ways to turn it back into clean drinking water, vs desalinization which requires a lot of energy still.

But it's not just sewage though, it's chemicals as well, e.g. from medication, plus whatever else gets flushed.

Exactly: all the sewage systems I know of process it enough to dump into a sea or river, where even if a downstream town draws drinking water from it the dilution with other water plus additional environmental chemistry reduces the purification problem.

In Singapore's case the sea is the obvious sink for treated sewage, which kicks it back to desalination. Except that I believe that Singapore's water comes across the causeway to the mainland in a pipe.

https://eu.usatoday.com/story/tech/2015/06/02/singapore-wate...

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