[PDF]Pour-Flush Water-Seal Latrines in India

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Manual on the Design, Construction and Maintenance
of Low-Cost Pour-Fiush Waterseal Latrines in India

by A.K. Roy et. al.



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Technology Advisory Group
World Bank
1818 H St. N.W.
Washington D.C. 20433
USA



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TAG Technical Note Number 10



United Nations Development Programme
Interregional Project INT/81/047
Executing Agency: The World Bank



Manual on the Design, Construction
and Maintenance of Low-Cost
Pour-Flush Waterseal Latrines in India

By A.K. Roy, P.K. Chatterjee, K.N. Gupta,
S.T. Khare, B.B. Rau and R.S. Singh:
Technology Advisory Group (TAG)-India





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UNITED NATIONS 1981-1990



A joint United Nations Development Programme
and World Bank Contribution to the International
Drinking Water Supply and Sanitation Decade



Copyright 1984



The International Bank for Reconstruction and Development /THE WORLD BANK
1818 H Street, N.W.
Washington, D.C. 20433, USA



All rights reserved
Manufactured in the U.S.A.



TABLE OF CONTENTS

Page

Preface .... . i

Foreword ..................... n

Chapter I: Introduction 1

Chapter II: technology and Design .......... • * 4

Pour-flush latrine ................... 4

Design and materials for latrine units c... 4

Squatting pan 4

Trap ..... • 4

Foot-rests 5

Connecting drain or pipe to pits 5

Leach pits ..*..••... 5

Size and shape 5

Siting 6

Location • ... ^ 7

Distance between two pits • • • . . • • 7

Distance from existing structures 7

Depressions and water-logged areas 8

Location in drainage line •••• 8

Water pollution aspects • • ••••• 8

Safe distance from drinking water sources 9

Safe distance from water supply mains 11

Viral pollution 12

Lining of pits • , , 12

Brick or stone masonry lining • 12

Use of rings for lining ••••••••«• 12

Pit covers 13

Suitability of leaching pits In black cotton soil 13

Standard designs 13

Superstructure for latrine •••••• 13

Community latrines 14



Page



Chapter III: Institutional Requirements 15

A Suitable Institution 15

Orientation and training . .. • 16

Methodology for construction of household latrines . . 16

Communication support: publicity, promotion and health

education .••»....••.. »•••• 17

Procedure for getting a latrine constructed 17

Supervision charges *. ...... .................. 19

Legal amendments . ... • ••••••••• 19

Chapter IV: Mobilisation of financial resources 21

Financing pattern • 21

Disbursement of funds 22

Recovery of loans ......... ^ 22

Repayment by the local authority to the lender 23

Chapter V: Construction * . 24

Materials 24

Materials to be supplied by the Implementing agency 24

Materials to be arranged by the contractor • • 24

Slabs for covering pits and junction chambers ••• 24

Casting of RCC slabs and domes 24

Stone slabs • • • 25

Fixing of pan, trap and footrests • 25

Connection to pits ............ •••.••••*•** • • 25

Drain • • 26

Pipe . 26

Junction chamber • •* 26

Lining of leach pits ••• • • 26

Brick work • 26

Stone masonry • 27

Stone pitching 27

Burnt clay rings «• • • * • 27

Curing 28

Flooring 28

Site clearance • 28

Specifications ...*....••• • • * • 28

Supervision •••••••••••••• 28



Page



Chapter VI: Operation and maintenance 30

Maintenance of household latrines • • • 30

Operation and maintenance of public latrines 31

Annex I: Studies conducted 32

Annex II: Drawings

No. 1 Pan and trap 33

No. 2 Drain and function chamber 34

No. 3 Foundation and plinth of superstructure... 35

No. 4 Details of superstructure 36

No. 5 Latrine with leach pits within premises 37

No. 5A Design of RCC covers ...» 38

No. 6 Details of reinforcement for RCC slab • ••• 39

No* 7 Latrine with leach pits under foot-path 40

No. 7A Details of pit roofs 41

No. 8 Details of reinforcement for RCC dome for pit

under footpath 42

No. 9 Latrine with leach pits under road ....*..*.*....... 43

No. 10 Details of reinforcement for RCC slab and dome

for pits under road 44

No. 11 Layout plan of leach pits in different situations. •• 45

No. 12 Layout plan of leach pits in different situations... 46

No. 13 Pits within the premises in water logged areas . .... 47

No. 14 Community latrlne-S seated 48

No. 15 Community latrine-12 seated 49

No. 16 Community latrine- 16 seated 50

No. 17 4, 6, 8, 10, 12, & 16 seated community latrine,

detail at A 51

Annex III: Estimates

Conversion of bucket/dry latrine with leach pits

within premises 52

Conversion of dry/bucket latrine with leach pits

under footpath •••• • * 54

Conversion of dry/bucket latrine with leach pits

under road ••••• 56

New pour-flush latrine with leach pits within premises 58

New pour-flush latrine with leach pits under footpath .......... 60

New pour-flush latrine with leach pits under road 62



Page



Covered brick drain ....... 64

Junction chamber . • • •••••• 65

Foundation and plinth for superstructure . .... ... 66

Superstructure of latrine cubicle • . . 67

Leach pit within premises 68

Leach pit under footpath • 69

Leach pit under road ••••• • ••• 70

Community latrine — 8 seated . . • 71

Community latrine — 12 seated 73

Community latrine — 16 seated • •«» • 75

Materials and labor required for conversion of dry

latrine with pits within premises • 77

Materials and labor required for conversion of dry

latrine with pits under footpath 78

Materials and labor required for conversion of dry

latrines with pits under road 79

Materials and labor required for construction of a new

latrine with leach pits within premises • 80

Materials and labor required for construction of a new

latrine with pits under footpath • 81

Materials and labor required for construction of a new

latrine with leach pits under road • 82

Annex IV: Forms 83

No. 1 Notice 84

No. 2 Application for construction of a pour-flush

latrine to be given by house-owner 85

No. 3 Application for construction of a pour-flush

latrine to be given by tenant 86

No. 4 Recommendation of the technical authority

of the implementing agency • 87

No. 5 Certificate for locating the pits under

footpath or road ••••••••••••• 88

No. 6 Letter to the applicant sanctioning the

construction • « 89

No. 7 Loan agreement with the beneficiary 91

No. 8 Work order and intimation to house-owner •••• 94

No. 9 Completion certificate 98

No. 10 Instruction for operation and maintenance of

pour-flush latrines 100

No. 11 Guarantee card 103

Annex V: Model by-laws for regulating the construction,

operation and maintenance of latrines 104



i



PREFACE



This manual on the Design, Construction and Maintenance of
Low-cost Pour-Flush Waterseal Latrines in India is one of a series of
informal Technical Notes prepared by TAGJ7 on various aspects of water
supply and sanitation programs in developing countries* The papers were
originally prepared as internal discussion documents; their wide
distribution does not imply endorsement by the sector agencies, government,
or donor agencies concerned with the programs, nor by the World Bank or the
United Nations Development Programme. Comments and suggestions on the
papers should be addressed to the Project Manager, UNDP Project INT/81/047,
Water Supply and Urban Development Department, The World Bank, 1818 H
Street, NW, Washington, DC. 20433.



SUMMARY



This manual has been prepared for agencies, contractors and
individuals involved in various aspects of the low-cost pour flush
waterseal latrine program in India. The inherent principles are, however,
of general application, and, with minor modifications, the technical
details can be readily adapted to meet the needs of different areas,
particularly where water is used for ablutions. The manual provides the
salient features of design, construction and maintenance as well as the
administration of low-cost pour-flush waterseal latrines with off-set twin
pits. It contains extensive drawings, tables of quantities of materials
for different designs as well as standard forms for by-laws and for general
project administration and supervision.



1/ TAG: Technology Advisory Group established under the United Nations
Development Programme Global Project GLO/78/006 (renumbered on January
1, 1982; now UNDP Interregional Project INT/81/047), executed by the
World Bank.



Cover photograph: Richard Middle ton, TAG



ii



FOREWORD



There is no denying that safe water supply is a very important
component in the overall strategy for achievement of health goals; hut the
rewards can be fully reaped only if sanitation keeps pace with provision of
water supply* Unfortunately, developing countries which are buckling under
the pressure of scant resources have not been able to lend support to this
philosophy and have perforce to adopt a piecemeal approach. However, the
situation is not bleak, since the commitments with regard to safe water
supply are almost well nigh fulfillment and the time is fast approaching
for bestowing serious thought on this aspect of sanitation.

Perhaps water supply has been able to attract attention of the
people not only because of its health Implications but also from the view
point of being a convenience for which the community is willing to pay.
Proper disposal of domestic wastes, however, has not this advantage and
motivation has to be to a greater degree than in the case of water supply.
Tha traditional system of conservancy has to slowly give way to alternative
cleaner and safer systems because of:

(*0 the health considerations associated with exposed night soil,

(b) the desire of the community for a cleaner and aesthetic system
born out of the rising living standards and education, and

(c) the society *s demand for doing away with the degrading practice
of human beings carrying night soil loads.

The sewerage system which has been the solution in developed
countries and warrants heavy investments could be afforded only by very
large communities and is far beyond the paying capacity of the smaller
communities. Moreover, this will call for a high technology with
sophisticated treatment systems with proper qualified personnel for
operation and maintenance. There Is, therefore, an urgent need for
evolving a viable alternative which has several of the merits in-built,
environmentally and aesthetically sound and within the easy reach of the
community. The International Drinking Water Supply and Sanitation Decade
has for its targets the adoption of sewerage system for all Class I cities,
with other low cost sanitation measures being adopted in other towns to
give an overall coverage of 80%.

Considerable research and development has been witnessed in the
country in the evolution of low cost methods. The "Low Cost Sanitation
with On-site Excreta Disposal System" developed by the UNDP Global Project
eminently meets witb all the promise of a safe and sound system and can
serve as an intermediate technology within the affordable reach of and
immediate adoption by several urban communities in our country. The
Project Team of the UNDP Global Project have worked out all the design
criteria for the pan and trap and the dual pit along with the cost involved
in the "Water Seal Pour-Flush Latrines*" Workability of this system has
also been established through a few demonstration projects.



iii



However, the need for bringing home the message to the people and
promoting its large scale use would be the immediate charge of all those
concerned with sanitation. Sanitation, if it has to succeed, must be made
'a way of life', and it is time that we got into this serious business of
entering into a direct dialogue with the people, whose participation in the
sector, more than elsewhere, we need in a large measure if our endeavour
has to be crowned with success.



(V Venugopalan)
Adviser (PHEE) and National Director for
UNDP Project on Low-Cost Sanitation,
Ministry of Works & Housing,
Government of India



ACRONYMS USED IN THIS MANUAL



AC Asbestos Cement

AIIHPH All-India Institute of Hygiene and Public Health, Calcutta

CBRI Central Building Research Institute, Roorkee

cm Centimetre

cu Cubic

dia Diameter

ES Effective Size (of soil)

GRP Glass Fiber Reinforced Polyester Plastic

GOI Government of India

HDPE High Density Polyethylene

ISI Indian Standards Institution

ISS Indian Standard Specifications

m Metre

mm Millimetre

m 2 Square Metre

m3 Cubic Metre

NEERI National Environmental Engineering Research Institute, Nagpur

PHED Public Health Engineering Department

PRAI Planning Research-cum-Action Institute, Luc know

PVC Polyvinyl Chloride

PHD Public Works Department

RCA Research-cum-Action

RCC Reinforced Cement Concrete

RR Random Rubble (used with stone masonry)

Sq Square



TAG Technology Advisory Group, UNDP, operating under UNDP Project

INT/81/047, executed by the World Bank

UNDP United Nations Development Programme

UNICEF United Nations Children's Fund

WHO World Health Organization



CHAPTER I
INTRODUCTION



1.1 Human excreta is associated with more than fifty diseases and it
causes nearly 80% of sickness in India. With proper disposal of human
excreta by inexpensive methods, these diseases can be brought under control
and the entire sanitation situation of the country can be improved.
Studies have established that without proper sanitation the full health
benefits of providing safe water supply are not achieved.

1.2 To begin with, all existing dry latrinesjV should be converted
into water-flushed ones to reduce the present insanitary conditions;
subsequently, sanitary latrines should be provided for use of householders
who have none at present. Sewerage and sewage disposal would have been the
ideal solution but the cost is prohibitive. Even with fairly intensive
efforts over the 30 years since the launching of the National Water Supply
and Sanitation Program in India, only about 200 out of 3,245 towns have
been sewered. The coverage even in these towns is partial (hardly 10-30%
houses have service connections). On account of prohibitive costs, even
the targets for the International Drinking Water Supply and Sanitation
Decade of the country restrict sewerage to Class I cities (population
100,000 and above) and envisage overall coverage of only 80% of all urban
areas (including Class I cities) with either sewerage or sanitary toilets.
Septic tanks with proper effluent disposal could be an alternative, but
these require periodic safe removal and treatment of the accumulated liquid
sludge, a service which has often proved unreliable. The septic effluent
is also a potential medium for mosquito breeding and may cause health
hazards if not properly disposed of through sub-surface drainage systems.
The high cost of septic tank systems put them beyond the reach of average
households; this has led to the search for alternative, more affordable
solutions. Pour-flush waterseal latrines with excreta treatment in twin
leach pits obviate these disadvantages; they are economical, and offer a
long-term and appropriate solution for excreta disposal until provision of
a sewer system can be afforded. Then these latrines could be connected to
sewers at minimal cost. This system will result not only in the relief of
insanitary conditions but will also eliminate insect and fly breeding due
to open defecation, as well as minimizing hookworm and other infestations
which reduce human productivity.

1.3 It could be argued that this solution would be feasible only in
rural areas, where the population density is low and the required space
might be available, and that it may lead to pollution of groundwater if
adopted on a large scale in urban areas. So far more than 400,000
pour-flush waterseal latrines have been constructed in the towns of India,
many in densely populated areas. House-to-house information covering the
entire households in over 110 representative towns surveyed under the
United Nations Development Programme (UNDP) Global Project on Low-Cost



If Bucket privies, emptied by scavengers



- 2 -



Water Supply and Sanitation (1979-81) has revealed that feasibility in any
particular urban area varies from 75% to 100% of the households concerned.
An Expert Group on the leaching pit system of latrines, formed by the
Technology Advisory Group (TAG) -India and consisting of eminent scientists
and sanitary engineers of India, made an In-depth study of the design
criteria for pour-flush latrines. After assessing a number of research
studies carried out around the world on groundwater and soil pollution
aspects, it was concluded that there is no risk in adopting this system in
the vast majority of hydrogeological conditions and that even in many
unfavorable conditions suitable remedial measures can be taken. More
details are provided in Chapter II.

1.4 GOI sought the assistance of the UNDP Global Project GLO/78/006
(now renumbered as INT/81/047). The Projects INT/81/047 and IND/81/014,
with the World Bank as the executing agency, have recommended in their
feasibility studies a design which takes into account the various
parameters developed not only in India but also elsewhere and their
critical evaluation from various aspects, including considerations of
technical and social feasibility and cost-effectiveness.

1.5 Pour-flush waterseal leach pit latrines were first developed in
India in the mid- 1940s at the Singur field center of the All-India
Institute of Hygiene and Public Health (AIIHPH), Calcutta. Since then
further development and research have been continued by this Institute.
The technology was originally meant for rural areas. The main design
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