Low Cost Sanitation in Tropical Slums

Outline Background - Slums and Sanitation Criteria for selecting sanitation technologies Comparison of available technologies

Background: Slums “unfit for human habitation” “very poor” “densely populated” - Oxford English Dictionary Definition: Population increase by 58 million/year - due to rural-urban migration 890 million by 2020

Background: Slums 23 million people lifted out of slum conditions every year (UN) A decreasing proportion of urban populations live in slums

Background: Slums Wide variety: building materials, population density, layout, ground conditions...

Sanitation – diseases Pathogens in excrement Transmission  Ingestion  Insects  Skin Mosquito reduction important

Background: Sanitation Objectives:  Increased life expectancy  Improved quality of life  Poverty alleviation Linked with  Hygiene education  Water supply

Selection Criteria  Health improvement  Economic feasibility  Technical feasibility  Cultural acceptability  Ownership  Institutional support

Technologies Focus: Pit latrines Simplified sewerage Too expensive: Conventional sewerage Septic tanks Holding tanks & collection

Pit latrines: Features Odour reduction Mosquito reduction Permeable walls $200 per unit VIP Latrine

Pit latrines: Assessment Cost effective Hygienic Independent of institutional backing  Space issues  Ground issues  Water-table issues  Sullage disposal

Simplified sewerage: Features Cheap version of conventional sewerage Narrower pipes Shallow gradient Peak flow used to clear pipes Shallower depth Fewer, simpler manholes Often combined with pour-flush toilets

Simplified sewerage: Assessment Far cheaper than conventional sewerage Excellent hygienically Cultural acceptability  Capital cost  Requires extensive institutional support  Sewage treatment required

Cost comparison Source: D. Mara, Leeds University Simplified sewerage is cheaper at high population densities

Conclusions Slum populations are increasing due to rural-urban migration Low cost sanitation technology plays an crucial role in improving the conditions of slum inhabitants Sanitation must be designed to suit local requirements and implemented in conjunction with health education

Conclusions Simplified sewerage Very high level of sanitation Most cost effective if widespread take-up Pit latrines High level of sanitation Feasible with less institutional support

Questions?

Technologies – Toilet Design Hole in floor Health improvement Economic feasibility Cultural feasibility Technical feasibility Cistern-flush GOODPOORGOODPOOR Pour-flush GOODVARIABLEGOODVARIABLE No-flush VARIABLEGOODPOORGOOD