May 292013
 

Latrine


Latrine is a safe place for proper disposal of human excreta. Disposal of human excreta in open places causes different environmental and health hazards. A latrine is a communal space with multiple toilets designed for defecation and urination. Latrines allow for safer and more hygienic disposal of human waste than open defecation.

They are used in rural areas and low-income urban communities, with significant use in the developing world. Many variations exist, but at its simplest, the reason for using a latrine is that waste is controlled and decomposed into safer by-products. Proper use of latrine helps to maintain environmental sanitation. According to the available place, size of family and economic status, the latrines are constructed in different ways.

Types of Latrine

Typically the latrines are categorized under two groups viz. service type and non service type latrine. Some of the commonly used latrines in our context are discussed below:

Simple Pit Latrine

Pit latrines are designed for the onsite disposal (but not treatment or reuse) of human excreta, with no or very little water use. They consist of a concrete squatting plate or riser, which is placed over an earthen pit. The design life varies depending on the number of users (several years to 10 years or more). Often, the pits fill up faster than originally expected.

The pit diameter is between 1 and 1.5 m. The depth of the pit is at least 2m, but usually more than 3m. The top (0.5 m of the pit) always require lining. In loose soil, the entire pit should be lined in order to prevent collapse. The liquid (urine and water content of faeces) is normally designed to be absorbed into the soil (otherwise the pit will fill up faster). One unit can serve one or several households. If constructed properly, pit latrines can be regarded as superior to the other alternative of open defecation.

Pit toilets, or pit latrines, are the simplest and cheapest type, minimally defined as a hole in the ground. The most basic improvement is installation of a floor plate. A dry pit does not penetrate the water table, while a wet pit does. It is simplest type of latrine which is suitable for hill areas. It can be made by digging a pit of small or large size according to the size of family. It can be constructed by utilizing the locally available materials.

Though it is easy and cheap to construct the following points are to be considered during the selection of site for a simple pit latrine.

  • Pit should be about 30 feet far from house and water resources.
  • Pit should be constructed in hard structure of soil and below the water sources.
  • Door and ventilators of latrine should not be faced towards the house.

The simple latrine has the following advantages

  • No skilled labour required for construction and maintenance.
  • Low cost
  • Excrements are better contained than in open defecation.
  • Pit latrines use no water or very little water for flushing.
  • It can be constructed by the use of locally available materials like wood, stone, straw etc.
  • It controls the breeding of insects like flies.
  • It lasts longer for a small family.

Despite its advantages mentioned above, it has following demerits:

  • Since pit latrines involve soil absorption, there is a danger of groundwater contamination.
  • They cannot be used at all in crowded areas, on rocky ground, where the groundwater level is high or in areas periodically flooded.
  • Require access to open ground and digging of new pits or emptying of existing ones every few years.
  • Emptying of pits can be very difficult (may require manual labour, pits may collapse).
  • Usually high level of odour and flies.
  • Toilets cannot be situated in houses, hence lack of privacy and safety concerns, especially during night time.
  • It is difficult to dig a pit in every place.
  • Leakage from the pit may pollute water bodies through underground path.
  • Children and old members of family face problem if it is very far from the house.

 Ventilated improved pit latrine



The ventilated improved pit latrine was first time introduced in Africa in the 970s and has proved successful in rural areas in overcoming problems with flies and odours. It is the type of improved pit latrine that consist of vent pipe to the pit and fitted with fly screen at the top outlet of the pipe. It is one of the very improved latrine for simple pit latrine. The smell coming out from the latrine is transffered up by  chimney. There is a such type of mechanism developed in VIP latrines for smooth flow of air.

Egg laying insects like flies attracted by the ordours of the latrines coming from the vent pipe, but due to closed fly screen, flies are prevented to enter into the pit. But some flies can lay eggs by entering into the pit via squat hole. When the adult flies try to fly towards the light but due to closed fly screen, they will not able to escape and finally die and fall back into the same pit.

For smooth flowing of air into the pit, there must be proper ventilation services. By opening the door on the top and down will help in smooth flowing of air into the pit.

Water seal latrine

Water seal latrine, known as Sulav Sauchalaya, is the outcome of the improvements made in the design of primary types of pit latrines. It is widely used in urban areas and rural areas as well. It is little expensive than simple pit latrine but is durable and permanent. It consists of two pits connected to pan of latrine with the help of drain pipe.

This latrine consists of squatting plates of cement concrete with a smooth pan sloping back. A bend pipe is connected to the pan tohold water and act as seal to prevemnt the smell from excreta. A drain pipe carries the excreta to the pit constructed with suitable mechanism. As pit is to be constructed, site for it must be selected as in simple pit latrine. This latrine can also be constructed within house for further convenience.

Water seal latrine has the following advantages

  • It prevents the spread of odor and movement of flies.
  • It can be constructed with simple technology and is long lasting.
  • Children and old people can also use, as can be constructed even inside house.
  • It is more durable as cement, sand, iron, bricks like materials are used.
  • Suitable for the places with plenty of water supply.

Water seal latrines has the following demerits

  • It is expensive to construct and trained persons are required.
  • Needs more water for flushing, so is not suitable for the areas with shortage of water.
  • It requires regular cleaning, if it is inside house
  • It is an expensive technology.
  • It needs some storage i.e. septic tank and sewerage.