Brain teaser 4 We use faeces (dung) as a fertilizer to help our crops grow. So why worry about keeping it out of water and food? 1| 2|3|4|5| Next >>

So if faeces - human or animal - are to be used for fertilizer, they have to be left to decompose until there are no germs or parasites left. If you can, you should consult a health or environment worker on how long faeces should be left, depending on conditions. According to World Health Organisation guidelines, it normally takes two years — longer with wet conditions — for faeces and all the micro-organisms they might contain to decompose.

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