recovery of urine, which can be reused as fertilizer. Principle Urine diversion takes advantage of the anatomy of the human body, which excretes urine and feces separately. In a UDDT, the urine is drained via a basin with a small hole near the front of the user interface, while feces fall through a larger drop-hole at the rear. This separate collection – or ‘source separation’ – does not require the user to change positions between urinating and defecating, although some care is needed to ensure the right position over the user interface. Female users may find that some urine may enter the vault during normal operation. This is typically a small amount and does not significantly affect the function of the toilet. Separate treatment of the two types of waste is justified since urine is nearly sterile and low in pathogens, provided an individual is healthy. This means that urine can be readily utilized as a fertilizer or discharged with less risk to community. Human feces, on the other hand are high in pathogens, including up to 120 viruses and need to be treated well before it can be safely used in agriculture. The main two treatment methods are composting and drying. When feces are used without composting, it is called night soil, and is very smelly. Ash and/or sawdust are usually added to the feces chamber of a UDDT to speed the composting process. Of the two, ash decreases microbial activity faster. Whether the feces are handled on site or hauled to another location, the weight and volume of material is reduced by separating out urine. Additionally, treatment is simplified and faster. Urine diversion can also be used for composting toilets to reduce odor and reduce excessive moisture. Types of urine diversion devices Urinals Urine diversion toilet designs generally require men to sit or squat while urinating in order to avoid unhygienic splashing of urine. In cultures where men and boys prefer to stand for urination, urinals are a good complementary solution. Urinals – widely used by males at public toilets, restaurants, schools, etc. – work as urine diversion devices because urine is collected separately from feces. When urinals do not use water for flushing (called "waterless urinals"), they can collect the urine pure, meaning without dilution with water. Suppliers for waterless urinals can easily be found on the internet. Urine-diversion flush toilets (UDFTs) Urine diversion flush toilets have