Sanitation and Wastewater Atlas of Africa

FLUSH TO SEWER

FLUSH TO SEPTIC TANK

PIT LATRINE

OPEN DEFECATION

Shelter

Slap with drop hole

Manhole

Ground level

Cover

Liquid level

Pit

Outlet pipe to leaching area

Inlet pipe from home

Scum Clear water

Sludge

Main sewer

Figure 2.1 . Visual presentation of existing household sanitation facilities in Africa

Table 2.1. Overview of existing household sanitation facilities in Africa

Open defecation

Pit latrine

Flush to septic tank

Flush to sewer

Use: • Geographical

Common in areas where people are too poor to build latrines, lack government support in providing such facilities or where there are cultural issues related to sharing toilets.

Two options: (1) Unlined pits that allow infiltration, applicable in areas with a low water table; and (2) Lined latrines with sealed walls and bottom to prevent infiltration, applicable in areas with a high water table and/or congested areas.

Appropriate in urban/peri-urban areas where there is a way of disposing of the effluent and at a location where an emptying truck can easily access it. This is the preferred option for waterborne sanitation in areas where there is no sewer network.

Preferably where there is a constant downhill gradient to maintain self-cleansing flows.

Individual level (Not recommended)

Household level

Household and institutional level

City or municipality level

• Number of people

Not recommended

Rural/peri-urban

Urban/peri-urban

Urban

Common location

Typical: • Positives (+)

+ Built and repaired using locally available materials + Low capital costs + Small land area required

+ Simple and robust technology + No electrical energy is required + Low operating costs + Long service life + Small land area required (can be built underground) – Regular emptying should be ensured – Effluent and sludge require further treatment and/or safe disposal

+ Very hygienic and comfortable for users

+ Greywater and storm water can be managed concurrently, where applicable + Can handle grit and other solids, as well as large volumes of flow – Very high capital costs; high operation and maintenance costs – A minimum velocity must be maintained to prevent the deposition of solids in the sewer – Requires deep excavations – Difficult and costly to extend when a community changes and grows – Requires expert design, construction and maintenance – Leakages pose a risk of wastewater exfiltration and groundwater infiltration and are difficult to identify

– Could easily lead to outbreak of communicable diseases such as cholera, typhoid and diarrhoea – Causes air and water pollution when human faeces are washed away during the rainy season

– Flies and odours are normally noticeable – Potential groundwater contamination

• Negatives (–)

– High emptying costs – Secondary treatment/ management of sludge required

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SANITATION AND WASTEWATER ATLAS OF AFRICA