Water-borne diseases had a much looser grip on the Japanese population than those in Britain.

In most cases, the human waste is used on grain crops, which are eventually cooked, minimizing the risk of transmitting water-borne diseases.

According to the World health Organisation, water-borne diseases such as diarrhoea, jaundice, typhoid, cholera, polio and gastroenteritis represent the single greatest threat to global health.