Starting from the Reality – Bottom-up WASH Techniques

This post wishes to provide an interesting account of some widely used bottom-up WASH techniques in Africa. Due to government failures in public WASH service provision, these techniques present a compromised yet essential WASH solution. Understanding these techniques allows later exploration of their weaknesses, potential improvements, and complementary solutions for successful WASH improvements.

Water-accessing techniques

Without adequate piped water supply, hand-dug wells, which citizens themselves can construct and operate at low costs, are a traditional and common water-accessing technique. The water in the well can be extracted using a pulley device or, preferably, a sealed handpump. A proper structure that prevents the seeping of surface water and filters silt and sand, illustrated by fig.1, can ensure water safety. 

Fig.1: The structure of a hand-dug well.

Comparably, despite moderately higher construction and operation costs, boreholes equipped standardly with a handpump provide a safer yet “man-powered and low-technology” technique. They are constructed with a drilling machine and feature better sealing and greater depths to reach higher-quality deeper aquifers (fig.2). Each borehole or hand-dug well fitted with a handpump is capable of serving the needs of 300 people (MacAllister et al., 2022). 

Fig.2: The structure of a borehole.  

I want to encourage reading this article by WaterAid, which provides a detailed account of rainwater harvesting, spring protection, subsurface dams and other bottom-up water-supply techniques that I cannot explore here. 

Sanitation techniques

In the absence of proper toilets and sewage networks, pit latrines (fig.3) provide affordable, easy-to-build, and acceptable (at least compared with open defecation) sanitation. On average, 65% of the African population was reported to rely on in-situ sanitation, mainly pit latrines (Tuinhof et al., 2017), with the number being higher in rural, peri-urban, and informal urban settlements. Following certain guidelines, including a depth of 3 metres, a location above the water table and more than 50 metres away from well or borehole, faecal wastes can be disposed of and degraded in relative safety. 

Fig.3: The structure of a simple pit latrine.

Water storage and treatment technique

The lack of pipes, taps, and water treatment facilities necessitates households’ own water storage and treatment practices. Fig.4 shows the general forms of water containers, often left open (Mellor et al., 2014). Boiling is the most attainable yet inadequately practised disinfection technique due to inconvenience and high energy consumption (Tumwine, 2005). 

Fig.4: Common water containers.

Without modern WASH services for many Africans, the reality is the adoption of these bottom-up WASH techniques.  I would like to briefly highlight that the adoption of these techniques is context-specific. For instance, fig.5 demonstrates the groundwater depth in Africa (BGS, 2011). While hand-dug wells may work for aquifers up to 25 metres below ground levels (mbgl), boreholes are required where aquifers are deeper.

Fig.5: Depth to groundwater in Africa. 

Do these techniques always perform appropriately? They don't for many reasons, raising or continuing WASH concerns, which I will explore in my next post with a case study.