The machine blends iron, bleach and sodium hydroxide to form a dark purple liquid mixture of ferrate, salt and water that gets metered into the water supply. (The color disappears instantly as it reacts with the water.) Common disinfectants ozone and chlorine can turn the water cloudy or, worse, leave behind harmful chemical by-products.

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Today everyone in the city, including in the slums, has access to potable water, only 7% of the water is "lost" (comparatively, in London 28% of the water is not metered or billed for) and the public utility is making money.

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There really should be a way to denote whether a spot is metered, covered by some wacky city permit law or submerged in a foot of water -- here's hoping the next update will enable comments.

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