On-site treatment is often (and should be) the first option when considering a sanitation intervention. Such systems have very distinct advantages, not at least, because they are individual systems, so the disposal of fecal material is dispersed over a wide area, and not centralized as with a conventional sewage treatment plant. One of the main disadvantages with centralized facilities is that when they go wrong, the resulting problems can be very acute.Very few sewage-treatment facilities in most developing countries work. This is often because most technologies for sewage treatment are big, centralized schemes which have been developed in the North where adequate financial, material and human resources are available. Transferring these technologies to tropical low- and middleincome communities has many potential difficulties.

From a health point of view, there is not much difference between any of the different options for sanitation - so long as they are all functioning properly. It is largely a question of convenience; an off-site system […] is more convenient as it gets rid of the problem from the owner’s property. Off-site treatment is usually much more expensive than on-site.

There are instances, however, where off-site sanitation is deemed necessary - because of unsuitable ground or housing conditions for on-site systems, or because of a community’s commitment to an off-site system. Once the decision has been made to implement an off-site system a sewerage system becomes necessity. Water has a large dispersion, dilution and carriage capacity, and therefore, it is used as the carriage medium in most sewer systems. Hence, most sewer systems are heavy users of precious potable water supplies, which should be a factor when considering their implementation, especially in water-poor areas.

(Parr et al. 1999)

The table above gives an overview about the advantages and disadvantages of on-site and off-site treatment.

Problems related to off-site and on-site sanitation systems are frequently reported. It was found that these systems are either inappropriate to the cities they are meant to serve, badly planned, badly implemented, or poorly managed. Other reasons were the gap which exists between the interests of households and the incentives of utilities/cities; the lack of resources and capacities; lack of focus on long-term operation, and no planned provisions for maintenance requirements. (Bahri 2009)

Most of the people in developing countries do not have access to safe sanitary systems. If we are going to tackle this problem we have to leapfrog the centralised end-of-pipe sanitary systems of the industrial world. New affordable technologies based on ecological sanitation, which save water, recycle local nutrients and extract energy, open sustainable options for all both in rich and in poor countries. (Jenssen et al. 2004)