Achieving ecological sanitation solutions does require a change in how people think about and act upon human excreta. In some societies human excreta are considered a valuable resource, and the handling of excreta poses no problem. In fact, urine has been used as a resource in many parts of the world for centuries. It was used in Europe for household cleaning, softening wool, hardening steel, tanning leather and dying clothes. The Greeks and Romans used it to colour their hair, and African farmers use it for fermenting plants to produce dyes. The Chinese pharmaceutical industry uses it to make blood coagulants. In other societies excreta, and in some cases particularly faeces, have been considered dirty for centuries. Experience shows, however, that urine diversion is acceptable, and the handling of urine poses far fewer taboos than does faeces. Many people do not know that faeces can be processed and converted into humus, with all the typical characteristics: pleasant-smelling, easy to handle as soil, and innocuous.