Overhung Latrine

An overhung latrine consists of a superstructure, which should be mechanically sturdy and safe for users, a latrine floor built on top of a wood, concrete, metal, or pole structure above water and situated along side banks of water or coastal flats. A squat hole in the floor allows excreta to fall directly or via a chute, into the water below (FARIS et al. 2002; HARVEY et al. 2002). The overhung latrine is a very basic system, and it should only be considered if other options are impossible (HARVEY et al. 2002). 

In areas where this type of installation is used, the contamination of the surface water (river, lake or other) is inevitable and it is a big challenge for affected communities to organise uncontaminated fresh water. Usually, they have to get fresh and drinking water from local vendors or need to walk big distances to a water source, e.g. a well (see human powered distribution). There might be tank trucks that bring water to the settlements. This generates high costs and not every government is willing or able to cover them. Otherwise, they may be forced to use contaminated water. To make the use of overhung latrines as safe as possible, the following criteria should be considered (FARIS et al 2002; HARVEY et al. 2002):

• The receiving water should be of a saline nature all year-round so that people are discouraged to use it for drinking.
• The receiving water must be deep enough throughout the year and should be flowing away from the settlement.
• The latrine is installed over such water depth that the water bed is never exposed during the dry season.
• Every effort should be made to select a site that would provide the transfer of floating materials and assist with dilution.

Regardless, recommendation for such type of latrine is only for those areas where conventional terrestrial types such as pit latrines cannot be built. In areas where water contact as means of seeking livelihood (e.g. fishing), transport or recreation/ bathing is a way of life, the system is never recommended (FARIS et al. 2002).

A solution to improve the sanitation problem in floating communities or dense settlements close to surface water bodies could be the concept of the floating latrine, which is described by BROWN et al. (2010). It is a similar concept like the UDDT system, but designed to install above water bodies such as rivers or lakes. Another solution for coastal areas is a hanging UDDT which is described by GENSCH et al. (2010).

The overhung latrine is a very cheap solution. It can be built with local material (wood, concrete, bamboo, metal, etc.). However, not everyone has access to an appropriate space to build an overhung toilet and people downstream and the environment have to pay a very high “price” for the damages which this solution creates.

Apart from keeping it clean, there is no daily maintenance. It is easy to operate and compared to a simple pit latrine there are no emptying activities since the river carries the excreta away. So the faecal waste can neither be disposed of properly nor can the nutrients be reused (e.g. use of compost). To guarantee the safety of the users, the supporting parts of the superstructure need to be replaced regularly (UNDP 2005).

Overhung latrines are used extensively in all urban slums located near surface water bodies such as rivers and lakes (UNDP 2005). The water body cannot decompose all this faecal waste thus leading to heavy contamination of the surface water sources (such as lakes, rivers or the coastal zones of the sea). Therefore local communities should be warned of the danger to health resulting from contact with or use of water into which excreta has been discharged (WHO 1992). Furthermore, there is a risk of coming into direct contact with the faecal water below the toilet when users fall into the water (e.g. bad construction of the superstructure) or when children play close to the water source.