File:Composting toilet with UrineDiversion-Dehydration.jpg

A shematic of a composting toilet with urine diversion and dehydration. The schematic is a modification of the File:Composting_toilet_ClivusMultrum.jpg Note that it is best to use 2 urine collection bins (instead of one as shown on the image) so that the sludge can be emptied (in an agricultural plot, similar to the compost) every once and a while. The urine collection bin is to be made of glass or of a transparent plastic matter (to allow solar heating). In some areas, it may be useful to add a black wooden board behind the urine collection bin. Note that just as with regular composting toilets, sawdust needs to be added in the appropriate C/N (carbon-nitrogen) ratio to the feaces to obtain compost. UDD toilets are extra useful in situations where weight plays an important role; eg on ships, ... they provide a speed advantage. Note that crops are best planted nearby that can be used as toilet paper (to retain a good quality humus). Examples are Brachyglottis repanda, Aralia spinosa, Oplopanax horridus, Platanus occidentalis, Arctium minus, Abutilon theophrasti, ... (see http://forums.gardenweb.com/forums/load/natives/msg0921305230090.html). Note that the seat has been simplified, see File:Composting toilet seat.png for the fully worked-out seat.