Across Southeast Asia many of the poorest communities live on marginal land or over water. Owing to adverse geographic and climatic conditions in these areas, neither conventional nor most well known 'alternative' sanitation options are feasible at affordable prices for poor communities or poor governments. A recent study in the region has started to develop a typology of challenging environments for sanitation as a means to: assess the scale of the challenges; understand the specifi c issues involved in improving sanitation; identify, develop or improve sanitation technologies to cope with different environments; and to disseminate the results in the study countries, regionally and beyond.

Across East Asia many of the poorest communities live on marginal land or over water. Owing to adverse topological, geographic and climatic conditions, neither conventional nor most of the well known ‘alternative’ low cost sanitation options are feasible at affordable prices for poor communities or governments. A recent study in Indonesia has started to develop a typology of challenging environments for sanitation as a means to: assess the scale of the challenges; understand the specific issues involved in improving sanitation; identify, develop, improve or adapt sanitation technologies to cope with different environments; and to disseminate the results in the study countries, regionallyand beyond. Four main challenging environment types were identified: coastal & estuaries: rivers and riverbanks, swamps and high water tables, and flood prone areas. Generally, challenging areas in addition to the limitation on conventional and low cost sanitation technologies were found to have the following characteristics:Open defecation into water is a common practiceCommunities use polluted surface and groundwater sources for domestic activities: bathing, washing, children playing, defecating (directly or indirectly), and even sometimes for cookingHouse patterns are unplanned and the areas may be densely populated by poor householdsOccupation is illegal or semi-legalThere is a lack of adequate access for de-sludging vehicles, due to narrow paths made of wooden planks, andHousehold access to clean water is a limited an therefore a high priority than sanitation The review of both technical and non-technical aspects of sanitation in these challenging environments confirmed the difficulties in implementing affordable sanitation options. Decentralized wastewater treatment systems from in-house or communal toilet facilities, are however options which have considerable potential in these areas, especially for overhanging houses, houses built on stilts and in-land houses.