With some types of sanitation, such as pit latrines, human waste can be filtered through soil. Across the world around 38 million tonnes of human waste is sanitised this way – the equivalent of around £3.2 billion of commercial water treatment Source: https://www.newscientist.com/article/2268469-soil-safely-filters-38-million-tonnes-of-human-waste-each-year/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home…