What Does Sanitation Look Like in Africa? Part 2 - Wet Systems

In the last post we looked at the types of dry toilet facilities, how they work, and the costs and benefits associated with their use. This included open defecation and multiple variations of latrine.This time round we will look at the facilities which do require water to function, wet systems.

A quick thing to note is that, as these facilities are all based on pits, there is the possibility for leakage into groundwater sources if too close.

Pour Flush Toilet

A pour flush toilet is a very similar concept to the toilets that we see in our homes in the UK, cistern toilets, except that the water is poured in manually to flush (SSWIM, 2018). The flushed out sewage then goes into a secondary pit away from the toilet to decomposes (figure 1). These toilets use on average 1-3 litres per flush, compared to the 13.6 litres (Home Water Works, 2018) used in the average cistern toilet and 6 litres if it is low flow.

Figure 1. Pour Flush Toilet (Image Source) 

The advantages of using this facility are that it is easy to construct, maintain and use, and it is also relatively low-cost. Pour-flush latrines wash away faecal matter from the site of defecation, reducing the presence of the bacteria which cause these diseases. The waste collected from the pit can also be used as fertiliser after it has undergone decomposition.

On the other hand, if there are any damages or blockages due to improper use or poor maintenance, piping parts may be difficult to locate and costly to repair. A frequent cause of blockages is the use of bulky materials for anal cleansing (wiping). There is also the issue of disposing of the waste from the pit. Whilst it may decompose after some time, it is not safe to dispose of until at least a year after final-use due to the time required for pathogen destruction. In the meantime, other sanitation methods will have to be used.

Similar to the double VIP latrine, in the previous post, the pour flush method can also have two pits, known as the double pit toilet. In this case the sewer pipe splits off into two different pits, with only one in use at a time. This system is advantageous as it allows for the same toilet to be used whilst one pit is left to decompose. The main issues with this toilet are that there potential for the second pit to fill before the already-filled pit is available to use and there may be leakage between pits if they are at too close a proximity, creating interruptions to decomposition.

Water Closet (WC) and Septic Tank Toilet

Figure 2. Water closet with septic tank (Image Source) 

This toilet uses a septic tank, a water-tight box that is split into two sections (NESC, 2018). After use, waste is flushed into the first section of the tank, in which separation of solids and liquids occurs. Solids remain in the first section in the form of a sludge pile, which the bacteria naturally found in the wastewater decompose. The liquids flow into the second section of the tank, leading into a 'soak away', allowing them to drain into the soil (UNICEF).

This toilet is hygienic to use as, before the next user arrives, waste is flushed away. As seen in figure 2, this toilet also has an inspection chamber, preventing against blockages that may be caused by cleansing materials. This allows for continuous, safe use of the toilet without the issue of harmful, pathogen-containing fecal matter backing-up into the vicinity of the user.

As this toilet is more complex, it comes with higher costs for construction and repair. It also relies on a connection to household water, in order to use the flushing mechanism. As the sludge needs to be emptied from the tank, it can only be built in areas with access to the emptying service. Therefore, this is only viable in communities established with these services.

Aqua Privy

Figure 3. Aqua Privy (Image Source) 

A simplified version of the septic tank, an aqua privy collects waste directly from the toilet and stores it for up to 5 years (SSWIM, 2018). The privy is filled with enough water so that the waste is completely submerged, preventing flies and mosquitoes from entering or escaping and concealing any smell.

This is less expensive than a septic tank as it is less complex and does not require piped water. This makes it relatively easy to construct. As waste flows directly into the storage area, materials for sanitation and cleansing cannot be put into the system. A restraint on this facility is that a sufficient amount of water is required to seal the waste and eventually the sludge must be carefully removed.

In all of these examples, the facilities are communally shared. This makes room for the spread of diarrhoeal diseases between those using the facilities. Although the wet systems flush away the fecal matter containing the harmful, disease-inducing bacteria, improper upkeep of the facilities, such as the toilet seat, will cause the facilities to become unhygienic and harvest these bacteria.

As these last two posts have made clear, there are a variety of sanitation systems within societies across Africa. Each of which with their own associated costs and benefits, and varying complexity. These facilities are by no means readily available to all who require them nor are they fairly distributed. The how and why of this is something that will be explored in future posts.