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eNote 5: Ventilated, improved pit (VIP) latrines

Author(s): Shaw, Rod (ed)  |  Shaw, Rod (ill)

Solid materials such as newspaper, corn cobs, leaves, sticks or stones used for anal cleansing are not suitable for use with pour-flush toilets as the water seal is likely to become blocked or broken. However, the addition of a vent pipe to a simple pit latrine is an alternative way of reducing the nuisance of flies in the cubicle if the cubicle is kept clean. This type of latrine is called a ventilated, improved pit (VIP) latrine. There are a number of designs to suit different situations but they all work in much the same way.

How it works

Wind blowing over the top of the ventilation pipe causes air in the pipe to rise. Replacement fresh air is drawn into the pit through the superstructure and down the toilet hole. This continuous flow of fresh air keeps the superstructure free of odours.

Controlling flies

Flies are also controlled using the vent pipe.

• The top of the ventilation pipe is covered with fly mesh. This prevents flies entering or leaving the pit via the pipe.
• The superstructure is kept dark at all times.
• The ventilation pipe is straight.

The last two factors work together to prevent any flies that may have entered the pit from leaving via the superstructure. Flies tend to migrate towards the light. Any in the pit will only see light at the top of the ventilation pipe since the superstructure is in darkness. They will be drawn towards the top of the pipe but cannot escape because of the fly mesh. They remain there until they die!

Spiral VIP latrines

VIP latrines work in part because they are dark inside. Keeping a conventional latrine superstructure permanently dark can be very difficult, particularly if it is used by children.

Children and casual users will be unaware of the need for darkness inside and may leave the door open. One way of overcoming this is to build the superstructure in the form of a spiral.

A door can be fitted if required but it is not necessary. Sufficient light will be reflected around the walls of the spiral to allow users to see what they are doing.

Disadvantages of VIP latrines

One of the main disadvantages of VIP latrines is that they have to be dark to work effectively. Children (and some adults) may be afraid – not necessarily because of the darkness – but because they may not be able to see if vectors such as rats, snakes or scorpions are hiding in the latrine.  

 

Keywords: Ventilated improved pit latrines (VIP)

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