Like dehydration toilet, sanitation systems based on composting are an effective method to deal with human excreta because they keep faeces that contain disease causing pathogens in a small volume in a closed Environment for a long time in order to be sanitised before reuse. They also produce compost that is rich in nutrients and is a good soil conditioner.

These systems have been increasingly applied in many parts of the world, mostly in rural areas and small communities. However, very few investigations on the composting toilets have been carried out so far (Naudascher, 2000). Investigations on pre-composting of faeces along with toilet paper and bark in small scale composting toilets showed that decomposition takes place in composting toilets, but only slowly because many factors that influence the composting process are, unlike in the pile system, difficult to be optimised in the composting toilet (Gajurel, 1998). Turning of the pile in the pile system helps for air circulation. It may not be practical in the present design of composting toilets. Moreover, because of the small amount of material entering every day and heat loss from the system, the temperature in composting toilets is more or less same to ambient temperature. The maximum temperature measured in the Multrum composting toilet was 32 °C (Jenkins, 1994). Another study by Redlinger et al. (2001) in the state of Chihuahua, Mexico, showed that temperature measured in single-vault solar composting toilet was equal to or similar to ambient temperature. The reasons they found were 1) the composting pile in the toilet was not large enough to trap heat to maintain the high temperature required for aerobic thermophilic bacterial growth, 2) users did not regularly adjust the moisture levels of the compost pile with water or soak materials, and 3) users did not regularly adjust pile oxygen content by stirring or turning over the pile.

Because of low temperature and slow decomposition, the materials in composting toilets should be kept in the vault for a long time in order to kill pathogens and to stabilise the composting materials. The pre-composted faecal material from the composting toilet has self heating capacity of about 60 °C. Therefore, it can be further composted in pile systems with other organic waste, in which many parameters influencing thermophilic composting can be optimised, so that high temperature can be obtained in the pile. Pathogen free stable compost is desirable for its application as fertiliser and soil conditioner.

Especially in dry climates dehydration toilets have been found more effective than composting toilets regarding pathogens destruction, volume reduction of the faecal material and maintenance. In dehydration toilets, because of dry conditions there is less chance of flies breading and odour development. However, the end product produced by the composting process is an excellent soil conditioner, free of pathogens when the optimal conditions are achieved and sufficient retention time is given. Therefore, development of composting toilets that can maintain optimal condition for composting of faeces is required.