Community Population Density Variation Implications on Sanitation System Cost – The Case of Kotoko Community in Suame (Kumasi), Ghana

Abstract

A significant global population proportion lives in densely-populated peri-urban poor communities with inadequate sanitation facilities.  When serving poor people with sanitation however, cost and affordability concerns dominate the discourse, besides space availability.  There is also evidence that sanitation system cost is a function of population density.  Population density strong influence on the most cost-effective sanitation system solution selection is therefore not in debate.    Though sanitation systems cost literature exists, very few (if any) link these costs to the varying community population densities triggered by global population explosion, urbanization, and climate change.  This research therefore looked at the effects of population density variation on sanitation system cost for a low-income high-density multi-ethnic peri-urban Kotoko community of 2,200 people in Kumasi, Ghana.  The community’s earlier studies identified simplified sewerage (SS) and ventilated improved pit (VIP) latrine as the most cost-effective.  These solutions were then subjected to population density and cost comparison with consideration for policy, socio-cultural and affordability influences.  The results revealed that SS was likely more cost-effective sanitation solution at the private level (one flush toilet per household) at an annualized household cost of USD46.  Simplified sewerage became cheaper than VIP latrine at a breakeven population density higher than 160 persons per hectare – a confirmation of Sinnatamby’s 1983 result for northeast Brazil.  Future population rises only made SS even cheaper.  Besides confirmation of SS as the better-cost option in high-density areas, this research showed that the breakeven population density at which SS was cheaper than VIP latrine varied with location.  This work also confirmed the growing evidence that people were already paying more for sanitation services.  The research concluded that SS was the first choice option for Ghana’s densely-populated peri-urban Kotoko community at all population densities over 160 persons per hectare.  To broaden the evidence base for decision-makers and allow determine whether the breakeven density for SS was unique to this community, it was recommended that more costing studies of this nature be carried out in similar communities in Kumasi.   The implementation of SS in the research community on pilot basis incorporating modern greywater use approaches for added benefits was also recommended.

Keywords: annualized household cost, population density, sanitation system cost, simplified sewerage, VIP latrine