3.5.1 Safe excreta disposal
Symptomatic and asymptomatic carriers shed large numbers of Vibrio cholerae in their stools for several days (Section 1.1.4). Thus, open defecation, defecation near water sources, or poorly constructed, situated or maintained latrines, can become sources of infection, particularly during the rainy season.
When there is a large concentration of people and no or few latrines, emergency measures should be implemented, taking into account the context and habits of the population (see also Section 4.6.3):
- Defecation fields
These provide a very short term (first few days) solution that can be set up in hot dry climates if there is enough space available and the population accepts them.
- Trench latrines
Trench latrines require less space and contain the faecal matter better (the stools are covered by soil located alongside the trench).
- Defecation in plastic bags
This option can only be considered if the following is organised: distribution of bags specifically designed for this purpose (biodegradable, single use, adapted size); information campaign on how to use them correctly; effective and safe collection, transport and disposal of bags by burial in an appropriate place.
These provisional measures should rapidly be replaced by less rudimentary solutions: improved trench latrines, simple pit latrines, improved pit latrines (public, shared or private), etc.
Note: toilets and latrines must have hand washing points that are constantly maintained and supplied.
For more information, see Public health engineering in precarious situations, MSF.
3.5.2 Waste water disposal
Prevention of cross contamination
Domestic waste water contaminated with human faeces may get in direct contact with potable water and lead to point source outbreaks.
These outbreaks are often caused by waste water leaking from septic tanks (or improper emptying of septic tanks) or from sewers, then contaminating the potable water system. Such water systems often work intermittently, allowing waste water flowing into the system via broken pipes at times of low pressure in the system.
It is imperative to determine the source of the contamination in order to remedy it (e.g. repair pipes) and disinfect the potable water networks polluted by the leaks.
Water drainage
Stagnant, undrained waste water is a permanent source of environmental contamination. Water pooling often happens in low lands or along coastal areas where waste water naturally collects and is difficult to evacuate. In urban areas, water pooling is often aggravated by discharge of domestic waste water by households, absent or obstructed drainages and, during rainy season, a raise in standing water levels.
There is usually no short-term solution for these situations due to the scale of the problem, the technical complexity of an intervention, the time and resources required, and the often illegal nature of the settlements (slums).
For more information, see Public health engineering in precarious situations, MSF.