Cover Image
close this bookWater and Sanitation Technologies: A Trainer's Manual (Peace Corps, 1985)
close this folderSessions
close this folderSession 15 - Excreta disposal systems
View the document(introduction...)
View the documentAttachment 15A: Improved ventilated pit latrine

(introduction...)

TOTAL TIME

Two Hours

OBJECTIVES

* Identify factors influencing the selection of a community excreta disposal system


* Describe various types of latrine design and evaluate their relative strengths and weaknesses


* List the construction steps for a ventilated pit latrine

RESOURCES

Sanitation Without Water; Winblad/Kilamer, Chapters 3, 4 and 5


Small Excreta Disposal; Ross Institute, Chapters 3, 4 and 5


Rural Water and Sanitation Projects; USAID, pp. 185-198, 209-217, 233-243, 261-266


Rural Sanitation Planning and Appraisal; Pacey, Chapters 1-5


Attachment 15-A, Improved Ventilated Pit Latrine Construction Steps

PREPARED MATERIALS

Newsprint and felt-tip pens

FACILITATORS

One or more trainers and four trainees

Trainer Introduction

This session is designed for trainee facilitation. Those who facilitate should be given ample time to prepare for the session. Make available any requested teaching aids prior to the session. The reading assignment is long, and trainees should be told well in advance.

PROCEDURES

Step 1

5 minutes


Present the objectives and format for the session.

Step 2

20 minutes


Facilitate a discussion to identify the factors influencing the selection of a community excreta disposal system. Encourage response from the trainees.

Trainer Note

Most trainees immediately think of latrine construction when asked to think about excreta disposal systems. Constructing latrines is an important step in a system, but it is by no means the only step. Below is a list of other factors that should be considered:

- traditional methods of Excreta disposal and hygiene practices
- social customs, beliefs, and taboos in this area
- types and numbers of systems already in place
- condition of existing systems
- geology of the area; soil types and water levels
- prevalent diseases and health care facilities
- human and material resources available
- level of community commitment towards improving sanitation

Step 3

1 hour


Trainees give presentations on four latrine types: simple privy with pit or bucket, ventilated pit latrine (VIP), off-set pit privy (Reid's Odourless Earth Closet, ROEC), pour-flush bowl and soakaway.


Question and answer periods follow each presentation.

Trainer Note

Each presentation should cover such factors as: design features, construction method, materials involved, cost, applications, hygiene, and maintenance requirements. The presentations should be organized and use appropriate visual aids such as drawings on newsprint. Feel free to substitute other latrine types in the presentations, if they are more appropriate for your training program.

Step 4

30 minutes


Hand out Attachment 15-A. Describe the following construction steps for a VIP latrine: site selection, foundation collar, pit excavation, slab, superstructure, roof, vent pipe, finishing, and maintenance.

Trainer Note

This step focuses on the VIP latrine because it will be the type of latrine constructed during Session 20. If you plan to construct a different type on your program, substitute that type for the VIP during this step.

Listed below are some important points to mention:

Site Selection:

Know the soils in the area and the ground water level.


Make sure the latrine is placed a safe distance, at least 30m, from any water source.

Foundation collar:

This footing defines the dimensions of the pit. It should be 12-14cm thick, and be similar in width. It should rise up higher than ground level when finished and can be made of concrete, soil/cement, brick, or wood.

Pit excavation:

The deeper the pit, the longer the latrine will be in use.


A formula can be used to calculate the pit size; (number of users) (years of use) x 0.06 = pit size. Three meters is a good average depth. Line the top portion of the pit as necessary to prevent the soil from caving in,

Slab:

It should be made of reinforced concrete and fitted to the foundation collar. Two holes are made in the slab, one for the squat hole, and the other for the vent pipe.


The slab should be placed to fit the superstructure design.

Superstructure:

This should be made from locally available building materials, and preferably, material that can be reused on another latrine when the pit is full. It should be constructed so that sunlight cannot penetrate inside and hit the squat hole. In this way, the squat hole needs no cover and air is allowed to circulate.

Roof:

The roof is made to fit the superstructure. It should be weather tight and allow no sunlight to penetrate inside and hit the squat hole.

Vent pipe:

Made of ferrocement, PVC pipe, or brick, it should be at least 150mm in diameter. The vent pipe should be placed outside, on the sunny side of the superstructure, painted black to cause a convection updraft which will draw air and gases from the pit, and be screened to prevent flies from escaping.

Finishing:

Interior walls and slab should be clean and smooth. They may be painted to facilitate cleaning.

Maintenance:

Cover slab should be cleaned regularly. Keep area around latrine clear and clean. Inspect the fly screen.

Step 5

5 minutes


Review objectives and conclude session.

REFERENCE: Rural Ventilated Improved Pit Latrines: A Field Manual for Botswana, The World Bank, Washington, D.C.