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What proportion of swimming pool water is wee? © Getty Images

What proportion of swimming pool water is wee?

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Researchers use the 'body fluid analogue' when studying swimming pool filtration systems, which looks at levels of sweat, urine, skin and faeces.

Asked by: James Smith, Edinburgh


When studying the effectiveness of swimming pool filtration systems, researchers talk in terms of 'body fluid analogue' or BFA. This is a mixture of sweat and urine, plus skin and faeces that represents the average concentration of pollutants from swimmers. Each person adds about 25ml of BFA to the water, 6.3 per cent of which is urea. The concentration of wee in a typical pool is about one part per million. Chlorine added to the water reacts with urea to remove it, but only about 1 per cent per hour is removed this way.


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Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.


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