&gt; They have a built-in, knee-jerk revulsion to drinking anything that came from sewage. That might not be rational or useful in 2016, but it has been tremendously useful over the past hundred thousand years of human social evolution.<p>That&#x27;s not necessarily true. First-world capitalist society focused on intellectual labor does a great job of mentally dividing the world into &#x27;clean&#x27; and &#x27;unclean&#x27;, where everything unclean moves invisibly through a series of subterranean pipes.<p>If you go to any farm, this division is much more vague. Farmers dump horse manure onto soil, from which your vegetables grow. Bruised and almost-rotting apples are picked, crushed, and pressed to create apple cider. Milk comes from the teats of a cow into a tin pail that might have some bits of hay that are later strained out.<p>The notion that humans have &quot;built-in, knee-jerk revulsion&quot; to sewage is a trained behavior arising from an ignorance or a visceral distance from production processes.<p>Many humans also probably have &quot;built-in, knee-jerk revulsion&quot; to the sight of animals being slaughtered, with their blood draining into a pool, yet will happily devour a plate of barbecue. Why would we consider that recycled water from sewage would be any different?