Chapter 11 Rural Water Supplies

220 CHAPTER 11

RURAL WATER WPPL IES I NTRODUCT ION The

concept

of

community

participation

s t a r t e d on a s m a l l s c a l e in t h e 1950's. grew d u r i n g the 1970's, l a r g e development significant development, were

upon

economic

development) economy.

the p r e v i o u s decade;

development "trickle

growth o r model

has

happened,

down"

The

spread

proved

in

that,

broadened a n d

to o t h e r

to

be

while

whereby

models

of

(e.g.

small

urban

industrial

as

the r u r a l

if

anything,

the

has

prospered,

the

and, elite

simplistic

(in

sectors such

invalid

a

i t has become a

early

were p u r e l y economic a n d

hypothesis,

i n one sector

benefits

would e v e n t u a l l y

This

reverse has

the

then

today

planning.

i n the immediate post c o l o n i a l e r a ,

based

terms)

in

The concept

development

in p a r t , b y the f a i l u r e of many of the

stimulated,

p r o j e c t s of

factor

community

in

l a r g e m a j o r i t y of the r u r a l p o p u l a t i o n h a s become poorer. There have areas

a r e exceptions

been

cases

(generally

the m a j o r i t y experience

those

also

the above of

large with

i n the area. showed

scale

course,

investment

good a g r i c u l t u r a l

Thailand

that

p a r t i c u l a r geographical i n fact,

to

where

there

i s one was

and in

undoubtedly

specific

potential)

such case.

no spread

there

geographical

have

benefitted

However,

the T h a i

of

benefit

outside

a r e a b e i n g assisted a n d t h a t

the net

result

the was,

a n o v e r a l l increase in the gap between r i c h a n d poor nationwide.

TECHN I C A L ASPECTS Surveys c a r r i e d out b y the World Bank and

sanitation

projects

surveys of boreholes

in

developing

i n d i c a t e f a i l u r e r a t e s in water

countries

in many a r e a s r e v e a l t h a t

as as

high few

SO%,

as

while

35 percent of

as

e x i s t i n g boreholes a r e o p e r a t i o n a l a t a n y one time. This

observation

in

no

choice i n a r u r a l water be t e c h n i c a l l y

viable.

way

diminishes

s u p p l y p r o j e c t since,

The c h a r t

water s u p p l y options most

in

likely

T a b l e 11.1 and

highlights rainwater.

supplementary s u p p l y ,

three

F i g u r e 11.1

sources of

Rainwater, i s unlikely

importance

ultimately, shows

to b e encountered.

can be d i v i d e d i n t o three p a r t s : source; water

the

treatment; supply

while

of

technical

the scheme must a

r a n g e of

Basically

rural

the system

and r e t i c u l a t i o n .

: groundwater,

capable

to become the m a j o r

of

surface

providing

source

due

to

a the

221

WASHING AND DRAWING WATER FR9M STREAM OR POND

a SLOW SAND F I L T R A T I O N

COMMUNAL RESERVOIR

TOWNSHIP

STANDPIPES

SINGLE DOMEST I C CONNECT IONS

Fig. 1 1 . 1

P U R I F I C A T I O N AND D I S I N F E C T I O N

M U LTIPLE HOUSE CONNECTIONS, HOT AND COLD, AND SA N ITA TION

E v o l u t i o n i n Water Supply Standards

limited r a i n f a l l

available.

specific a r e a s of

many

this

increase

source

present

will

time

majority

of

r e m a i n so

the

per

day.

is

of

in

the

near

the

major

the

distance from

for

throughout

then

handpump.

in

at

the

of

However, water

for

the

world

and

is

likely

standpipes.

fetch

Swaziland

water

from

10 t o 30P

per capita

be

relatively

appear

water. where

from

is

to

Accurate there

20

time of

50

and

the

is

domestic

collected

turn-around

between

level

storage

Here

much

rationalisation,

have

tank

over

a

figures

have

major

rural

a

use

(use of

supply)

averages

12

hour

day

on

2 a n d 5 minutes at

between

families

can

least,

reduced

be

served

i s given

s u p p l y programme.

options

to fo llow which

in the

by

one

shows a

corresponds

clear

documented

u s e of

to Oakley

a

the country. three for

and

A s i m i l a r system i s also o p e r a t i o n a l

area

of a

Zimbabwe

and

two

respectively

unsuitable,

training.

case study

specific

the

to

throughout

p i p e construction,

technically

interesting

of

the

Consulting,

and

final issues

i l l u s t r a t i o n o f one Lesotho r u r a l reasons.

19871,

but

participation

Community

the

b u t also the

An

for several

community

a n d Marsden’s

driven

that philosophy.

are

(M.6.

fuel

network

in

done

financial constraints,

following is

to

material

education a n d

This study

i s the approach well

types

one t y p e of

structure,

be

is a

supply

standardised

i f not throughout

choice needs to con sid er n ot o n l y of o r g a n i s a t i o n a l

water

to

being

handpump

other countries a r e beginning eliminated

simple

needs

equipment

a n d h a v e s t a n d a r d i s e d on

Having

and

still

work

with

geographical region at Mozambique

it

to

( T h e L e s o t h o o b j e c t i v e i s o n e p u m p p e r 20 f a m i l i e s . )

high

approach

to

usage from

source

The n e x t s t a g e in t h e d e v e l o p m e n t of t h e w a t e r s y s t e m pump,

potential

that

future.

the

would

to

permitted

that

a n d assuming a

pump,

in

limited

Here w a t e r c o n s u m p t i o n for domestic

is not

Given

figure

travelled

studies

gardening

25P/person/day.

the

are

i s expected

probably

population

Interestingly

obtained

average,

it

1979).

water s u p p l y programme. water

too

r u r a l water consumption f i g u r e s v a r y

independent been

rural

waters although

rapidly

groundwater

(Uphoff,

Typical

Surface

countries,

Development

water

Not o n l y

in a d d i t i o n

model, model

which (1984).

in S w a z i l a n d .

CASE STUDY The

Lesotho

management responsibie

system

system for

all

village and central whose

work

is

to

relies

where aspects

government explain

strongly

there of

is

9

the

OP

chief

developinent. i s handled b y

government

policy,

The d

traditional

and

a

villaae

relationship

rural

motivate

development the

village council between office,

community

for

x

SURFACE WATER

RIVER

LAKElDAM

I---4 MRECT

RURAL WATER SUPPLY OPTIONS

I

I I

I

1

1

RIVER

I

DEEP GROUNDWATER

I

I MECliANICALDRILLtNG

STORAGE

ym ' GRAVITY ""

I

GROUNDWATER

I

I

SPRING

1

1

I

SOURCE

I

I

I

I

I

RIVER

ROOF

STORAGE CONTAINER BOUGHT

I

PUMPING

GROUND

LOCALLY MANUFACTURE0

I

RECIPROCATING ROTARY HYDRAULIC RAM AIR LIFT CENTRIFUGAL AXIAL

I

I

I I

I STOPAGE

IVILLAGE SPRING

I HIGH LEVEL STOR,AGE

I L-, l i l BUCKET/MNMI ICOLLECTION PIPED USING SUPPLY

I, I

I

PIPED

SlPPL Y ICONTAINER C P W ~ D I (GRAVITY I I I I I 1 WTER T'ANK STANAPES H o u h I

I

IN VILLAGE

J

COLLECTION

I

I I

co"EcTIoNs

I STORAGE 7

N N

w

224 village

water

supply

work

participate.

The o f f i c e

procedures,

etc.

and

also

There

is

encourage

provides also

a

those

who

administrative

technical

seem

reluctant

assistance

division

within

Government,

c a l l e d the v i l l a g e water s u p p l y section o r VWS whose f u n c t i o n

is, to choose

t h e best technical o p t i o n f o r a p a r t i c u l a r

v i l l a g e a n d to work

to

Before

construct

installed,

the

village

a water

established.

water

committee

Because

supply.

which

Central

Government

determines p r i o r i t i e s w i t h i n the c o u n t r y , (e.9.

no.

of

people

served,

a

is correctly

whether

water for

w i t h people

supply

can

be

first

be

installation

it

constituted

pays

must

the

to

setting

in

based upon f a c t o r s such as need schools

and

clinics

are

present,

p o t e n t i a l f o r a n outbreak of disease in the a r e a ) , the degree of community interest,

and

technical

possibilities

for

construction.

However,

once

the

system has been i n s t a l l e d , ownership r e s t s e n t i r e l y w i t h the v i l l a g e . I n terms of c o n s t r u c t i o n t h e VWS f i r s t

v i l l a g e r s to shape stones f o r storage tanks, to

help

in o r g a n i s i n g

complete

the

labour

force.

will

arrive

VWS team

the f u l l

aspects of

the

project.

Once

in a

sends

to

to d i g f u r r o w s

When and

completed,

mason

two

the

the

is

village

and

minor

repairs

would

normally

be

carried

out

by

work

more

is

complex

responsible

l o o k i n g a f t e r the system a n d f o r c a r r y i n g o u t minor r e p a i r s . appointed b y the v i l l a g e a n d t r a i n e d b y the VWS,

the

for pipes and

t h i r d s of

supervise

the

teach

a

water

while for

for

Maintenance minder,

s u p e r v i s i o n of

the s u p p l y a n d d i s t r i b u t i o n system a g r o u p of v i l l a g e r s c a l l e d g u a r d i a n s Each committee h a s a t r e a s u r e r

would be appointed. bookkeeping, villagers paying

and

each

village

contribute and

the water

the

minder.

whole question of f i n a n c i a l of

the

project

and

a

then

income

Major

opens

i s used

repairs

management

significant

a

are

who

special for

spares,

handled

of

the

simple All

account.

diesel

by

i s seen as c r u c i a l

proportion

i s taught

bank

to

and

for

VWS.

the

the

training

The

success

effort

is

provides

a

devoted to t h i s issue. I t can be seen t h a t , "safety

net"

making at a

for

the

local

with

village.

level

t h i s system, Nonetheless

central there

is

government

a

degree

of

which would a p p e a r to be s a t i s f a c t o r y .

b o t h the Lesotho a n d the Swaziland schemes appear

decision Certainly

to be w o r k i n g

well

at

t h i s stage. DEVELOPMENTS I N SUPPLY Considerable

effort

p o t a b l e water (e.g.

has

gone

into

supplying

rural

population

with

ECLA, 1973).

Due to n a t u r a l preferences a n d relocations,

v i l l a g e s o f t e n occur

along

225

the crests of h i l l s i.e.

at

the f u r t h e s t p o i n t s from r i v e r s a n d a l s o where

the water t a b l e i s deepest. of

women and youths

t r a n s p o r t i n g water

of

method

in a l a r g e p r o p o r t i o n of the time

This r e s u l t s

(sometimes over 4 hours

from r i v e r s and

collecting

water

has

springs

a

to

reduced

day)

being

taken

the v i l l a g e s .

the

water

in

up

This

tedious

consumption

to

a

namely less than 4 l i t r e s p e r c a p i t a p e r day i n many cases.

minimum,

The World Health O r g a n i z a t i o n has suggested of 20 l i t r e s p e r c a p i t a per day

a

minimum

which would appear

water

supply

impossible w i t h many

Dresen t s i t u a t i o n s ( 1982). Attempts to Supply Water to Rural P o p u l a t i o n V i l l a g e s can That

is,

be c l a s s i f i e d

critical

depending

on

the

need

for

water

areas can be defined as those where there i s

10 l i t r e s p e r c a p i t a l of

water

a v a i l a b l e per

thousand metres to the nearest

water

source

day

and

and

supply. less

access

is

than

over

a

the g r o u n d slope a l o n g

that way i s steeper than 12%. On the o t h e r h a n d those which h a v e been 10

750 to

a n d 20 l i t r e s p e r c a p i t a p e r day of water a v a i l a b l e a n d l i v e w i t h i n

1000 metres of classified

as

a

water

needy

source

with

the

balance

and

a

slope is

of

6

between

classified

as

12% a r e

and

having

adequate

water supply. Cost of Rural Water Supplies P r i o r to assessing the o v e r a l l water,

investment r e q u i r e d to p r o v i d e adequate

the system of water s u p p l y

has

to be optimized.

I n other

words,

the most economical method of s u p p l y was considered as well as the method of conveyance and d i s t r i b u t i o n . The options open f o r s u p p l y of water i n c l u d e (see Table 1 1 . 2 ) :

1

Groundwater There a r e not many n a t u r a l s p r i n g s

p e r m e a b i l i t y of the far

below

the

u n d e r l y i n g rock,

surface.

It

example w i t h a w i n d m i l l , l i f t required. relatively, borehole

and

i s therefore

areas o w i n g

the groundwater

generally

necessary

to

table to

the

low

i s often

pump,

for

as h a n d pumps can often not cope w i t h the h i g h

I t also follows that the average cost of d r i l l i n g boreholes i s

high

plus

reticulation.

in drier

and

(together

windmill

can

be

with as

i n c l u d i n g a reservoir.

pump high

and as

The t y p i c a l

pipeworks)

$60

000

y i e l d of

the

per such

cost

scheme a

per with

windmill

N

TABLE 11.2

-

N

m

C o m m u n i t y Water S u p p l y Services i n D e v e l o p i n g C o u n t r i e s (Source: World H e a l t h O r g a n i z a t i o n , 1973) ( D a t a a s a t December 31, 1370) Urban population supplied

Region and Country

By house connections By public standposts

moo

x

~~

Total urban

Rural population with reasonable ~o~ access

lotal population

m&!Pl!ied?s

Sunnary for all developing countries: Africa Americas Eastern Mediterranean European Region South-East Asia Western Pacific Total Africa Botswana Burundi Caneroorl Central Africa ReDublic Chad Congo Dahomey Gabon Garnbi a

Ghana

Guinea Ivory Coast Kenya Lesotho Liberia Madagascar Mali Mauritania

R 876

29 60 59 50 36 65 49

I 1 921 26 724 16.726 5 426 26 798 3 668 91 263

39 17 26 22 17 10 19

16

150 16 30 80

46 15 13 4 11 28

19 60 750 34 170 198

33 5 10 652 337 260

9 5 27 22 75 28

31 3 1 26 I 483

1 000

95 38 12 56 25 236

410 093 406 391 107 283

15

5

60 236 160 80

Niyer Nigeria Senegal Sierra Leone Togo Uganda

40 2 810

United Republic o f Tanzania Upper Volta Zaire Zambia

100 40 1 205 705

300

102 34 400

797 134 819 832 189 775 546

68 76 84 73 53 75 68

54 62 64 9 65 69

35 75 900 50 200 278

100 77 77 13

66

656

70 51 22 70

346 6 36 2 135 437 916

90 19 43 25 26 91

72 22 50 594 20 6

77 81 57 63 3 7

1 072 27 140 830 160 86

12 22 29 27 13 58

180 4 650 722

55 36 69 53

220 7 460 1 022 282 248 616

68 58 98 75 97 89

570 3 586 2 178 26 86 1 600

16 8 74 1 5 20

11

400

54 68 55 97

1 200 1 MO

71

400 255

500 140 1 605 955

10 25 5 19

20 41

100

lBil

21 4 216 100

1

w

31

44 49 14

25

20 122 54 17 83 28 327

16 29 31 18 61 16 173

717 549 255 400 095 067 083

11 24 18 44 9 21 14

37 514 15i 683 86 074 36 232 144 284 44 842 500 624

21 54 33 55 17 40 29

184 75

29 2 32 3 26 34

149

25

1 000

21

76

780 46

22 7

50 980 324

94 6 97 73 97 97

455

19

Bill

9 870

3 14

1 000

29

3 005 437 1916

29 1 12 33 11 44

97

240

2

1 312

12

I00 8i 29 98

67 45

6

114

10

98

100

1

750 645

n

1

1 900

7

45

27 207 875 180 200 790

I I 046

3 200 308

334

3 17 12 33

17 20 20 81 12 18

2 716

25

1 700 1 440

25

2 355 1 600

13

13 37

227 could

15

be

cubic

metres

per

day

which

is

severe

would

provide

water

800

for

peop I e. may

It

be noted that

there

such circumstances since they a n d the number of working a borehole

the

can o n l y

hours a day

limitation

water on foot,

on

deliver

about 8

would

therefore

000 l i t r e s p e r d a y .

less than 4

to

to collect

a

hand

pumps

in

l i t r e s p e r minute, limit

the y i e l d of

I t would also be necessary

and the p h y s i c a l

effort

thus

required

would

p l a c e a severe l i m i t a t i o n on the system.

2 ) Surface Water Resources

There

are

many

successfully, that

such

available,

but,

regional in

schemes

i s considered dam,

a

some have

can

meet

and generally

The c a p i t a l cost of

supply

the water

perspective

station,

a

schemes

maintenance

minimum

of

can

cubic metre i s h i g h l y dependent supplies

delivered.

supply

may

magnitude

The cost with

if

not

The cost

F i g u r e 11.2

from

a

for

central

recognized

For

per

it

would

a all

and

per

and for

small

metre of

water

the cost

increases

reticulation but

water

instance

capita

cubic

pipe or

of

monitored.

works

i n d i c a t e s that

stand

is

h a n d unless

the project

$10 p e r

exceed

operating

adequately out of

achieved.

the scale of

allow

It

are

quantity

purification

the p o p u l a t i o n s u p p l i e d

also does

distribution

on

easily

On the other hand,

b y orders o f order.

the cost

get

benefit

and

n o r m a l l y be associated w i t h such a scheme.

scale

in

be

however,

the

pipeline

which

problems.

standards

quality

such schemes can,

i n the

pumping

water

by

reduces

the

assumes pattern

same

a

of

bulk stand

pipes.

3 ) Rainwater Collection Limited

research

has

been

done

impermeable covers and d i v e r t i n g

in

it

the

field

i n t o a tank.

of

collecting

The r e l i a b i l i t y

rain

by

and

the

in most cases.

cost however appears to r u l e t h i s method out

VALUE OF WATER

I n j e c t i n g money i n t o water s u p p l y result

in

employment isolated

improvement and

living

c i r c u l a t i o n of

construction

p r o v i d e s short

in

job

may

term employment.

schemes could, standards

money. be

On

due

the other

disrupting

Development

to

the

i f managed p r o p e r l y , to

the

hand,

to

society

authorities,

creation

of

provide

an

although

it

therefore,

appear

220 to

favour

continuity.

i n t e g r a t e d development T h i s encourages

l a b o u r i n t e n s i v e methods.

local

i.e.,

one scheme a f t e r another p r o v i d i n g

responsibility,

awareness campaigns a n d

The cost a n d need a r e not the o n l y c r i t e r i a

d e c i d i n g whether to s u p p l y a r u r a l v i l l a g e w i t h water. economical

type of

supply

throughout,

the cost

of

Even w i t h

s u p p l y i n g everyone

would be over $600 b i l l i o n .

Whether

everyone

b e n e f i t a p p r e c i a b l y from such water s u p p l i e s a n d ,

i n fact,

whether

the w o r l d w i t h

to

everyone

reasonably

water

justified,

perhaps

f u l l employment

is

a n d the

needs

use. Perhaps l a b o u r i n t e n s i v e type water many of the objectives sought

reassessment

people's

until

s u p p l i e s may

i n fact

in water resources development

to

in

would supply

there

time c o u l d be p u t

in

the most

is

better

be meeting

( p r o v i s i o n of

employment as a means of c i r c u l a t i n g money a n d

i m p r o v i n g the economy of

the

from

country).

transport

by

Labour

intensive

means of

animals,

methods to

range

simple

purification.

0

Fig.

1

2

3 L DISTANCE

5 6 7 FROM SOURCE

hand

gravitational

8

9 km

11.2 T y p i c a l Cost of R u r a l Water Supplies

drawing

feeds

with

and basic

A n a l t e r n a t i v e would be to s u p p l y water probably

where the cost

T h e people, where

the

from

if

they

services

migration

community. realised

including

the

many be

water

such

communities

However,

would

or

desirability

A f f o r d a b i l i t y of

electricity. there

i s reasonable

r e q u i r e water

and other desire

free

economy.

services

water,

having

The

may

services must

cannot

to

hope

employment

services

also

pay

possibility

and

are

available.

then

r e l o c a t e to

One could

such

then

detect

amongst

be considered. for

i f the economy were to grow

reasonable

a t selected positions,

a r e adequate.

of

nominal fee o r e v e n t u a l l y the f u l l fee, a

in b u l k

water,

let

the It

alone

to such a n extent

people

could

be

is

that

charged

a

t h i s would be a g r e a t step towards

of

coin

box

pumps

water

supply

could

also

schemes

is

be

considered. One advantage they

form

town,

a

of

node f o r

could

be

so

centralized

regional

A

settlement.

established,

c o u l d take some pressure o f f

the

community,

resulting land.

in

and

a

net

later

a

that

village

urbanization,

or

which

The continued support of scattered

r u r a l huts i s h a v i n g a d e v a s t a t i n g effect on soil conservation a n d f e r t i l i t y a n d i s denuding areas of n a t u r a l vegetation a n d trees. OPTIMIZATION OF BULK SUPPLIES Bearing

in

mind

methodology

for

a)

design

of

such

r a n k i n g that

the

advantages

r a n k i n g water

of

supply

scale

in

schemes a n d

schemes i s b e i n g developed.

It

is

water

supply,

a

b ) optimizing

the

implicitly

the schemes h a v e been i n i t i a l l y optimized i.e.

of each a l t e r n a t i v e has been reduced to a minimum.

assumed that

in

the cost

T h i s must b e done b y

systernat ic methods. Optimum Design of D i s t r i b u t i o n Networks An

example

scattered

of

villages

a

water

supply

is

given

below.

indicated previously,

has

an

scheme The

important

for

regional

a

scale,

i.e.

b e a r i n g on

size

community

or

of

as

the cost

pipes, per

unit

of

water s u p p l i e d , and therefore the r o u t i n g of the p i p e s should be such that the total are,

s u p p l y c a r r i e d t h r o u g h each p i p e i s as h i g h as possible.

however,

many possible routes a n d a l t e r n a t i v e b r a n c h

type

There

networks

v i l l a g e s w i t h i n a d i s t r i c t . Assuming t h a t each v i l l a g e r e q u i r e s a to SUDPIY supply of 20 l i t r e s per d a y p e r c a p i t a , l i n e a r programming exercise. in

Figure

11.3,

i.e.

the

the network c a n be set up

as

a

The r e s u l t s of such an a n a l y s i s a r e i n d i c a t e d optimum

supply

route

and

amount

of

water

N

w 0

d

w

c

0

C

1400

mmo 1 2 3 4 5 . 1 1 1 1 1

-

M H S IDENTIFIED

1000 = ELEWTION 6,97 II s = DEMAND OF THE UNIT IN 1 I s

X

=

DlRECTlMl OF FLOW PROPOSED PIPE R W T C BY THE PROGRAM LEAST COST DlSTRlFWTlDN WLUE IN LI TRES I SECOND ( I I I )

231

s u p p l i e d the v i l l a g e s a r e indicated.

APPL I C A T ION As a case s t u d y ,

the water s u p p l y to Umzimkulu was studied.

embraces 190 000 people i n 133 v i l l a g e s water

11.3).

and

the

The

computer

least

optimum

cost

which

distribution

system

bulk

supply

source

and

l i n e a r programming techniques

p a t t e r n proved

to

be 20% cheaper

have a t was

than

present

to

be

pattern

the best

delivered

selected

was

1984).

(Stephenson,

The a r e a

(Fig.

selected The

by

resulting

a l t e r n a t i v e obtained b y

hand. Shadow labour.

values

were

then

applied

to

construction

costs

for

use

The r e s u l t i n g d i s t r i b u t i o n p a t t e r n was however not affected

case as a l l construction

a n d o p e r a t i n g p r i c e s were

reduced b y

of

i n this

about

the

35%, to a l l o w f o r l a b o u r u t i l i z a t i o n .

same p r o p o r t i o n i.e.

WATER SUPPLY INDEX FOR RANKING PROJECTS

I n order

to

attempt

to

assess

and

prioritize

projects,

the

variables

were set down i n a formula as follows. Let

W 1 = water

supply

rate

in

years of operation,

ke/day,

f o r domestic,

averaged stock

over

the

first

10

a n d other uses where

the consumer cannot meet the a c t u a l cost. W2 = water supply r a t e i n k t / d a y

to i n d u s t r i e s a n d other consumers

who can p a y the water costs,

averaged over the f i r s t 10 years

of operation.

C 1 = c a p i t a l cost proportion x .

C2

= operating

of

proposed

project

Use ( I - x ) C 1

cost

$/annuin

w i t h chemicals and

f

Dollars,

in

pumping,

of

labour,

including

labour

xC1 K1 = C1 f o r WSI allowing

maintenance,

for

treatment

l a b o u r component

as

i n C, Labour cost = m a r g i n a l cost o n l y ,

where

K,

i.e.

K,

times s a l a r y .

= 0 f o r no a l t e r n a t i v e employment a n d local f u n d i n g . = 0.5 =

1.0

f o r no a l t e r n a t i v e employment a n d f o r e i g n f u n d i n g for

zero

unemployment

areas

i.e.

competing

employment

opportunities

R = availability breakdowns,

as

a

fraction

of

no supervision e t c ) .

time

(less

than

1

due

to

232 x 0.087 + C 2 )

W S I = 100 (C,

Then the water s u p p l y index, factor

0.087

+ W2)

(W,

36% T h e discount

i s based on 6% r e a l

discount

r a t e over

20

years. The

index

ranking, supply

should

e.g. rate

be

optimized

(minimized)

for

b y d e c i d i n g on minimum treatment per

capita

and

maximum

each

needed,

scale

of

project

before

minimum design

development.

Then

a l t e r n a t i v e schemes can be r a n k e d w i t h h i g h e s t p r i o r i t y f o r p r o j e c t s w i t h low

ws I .

APPLICATION OF WSI A p p l i e d to a l t e r n a t i v e sources of water f o r the selected case s t u d y ,

the

technique produced the f o l l o w i n g i n d i c e s : Borehole a n d w i n d m i l l WSI =

40

-

120 (40 based on based

on

80% a v a i l a b i l i t y ,

40%

120

availability

and

cost 1 y maintenance)

W S I = 140 - 240

or I RWSS

W S I = 100

-

with reticulation

140 reduced to -100

-

Borehole, pump a n d r e t i c u l a t i o n WSI = 130 The use of a water s u p p l y

280

index h a s enabled

s u p p l y schemes to be r a n k e d . The r a n k i n g

w i t h optimization.

alternative

i s not o n l y

intensive

integrated solution

regional

provided

cost water the

and

phased

supply

layout

and

construction.

scheme

appears

general

c a r e f u l l y , as i n d i c a t e d in the summary

water

based on cost,

includes factors f o r involvement of local people, r e l i a b i l i t y , operating

rural

capital

In the

scheme

but

versus

general, most

plan

is

the

attractive optimized

in Table 11.2.

TABLE 11.2 Type of scheme

L i m i t of c a p a c i t y

Handpump

4 000 t / d

C a p i t a l cost

Cost c/m’

$5 000

Prob I ems

40

Lcw Y i e l d / ca paci t y Ma i n tenonce

Windmill + dam

15.-20 000 e/d

$10 000

20

R i v e r pump

5 000 000 P/d

$ 5 000 000

30

Power,

$20 000

60

Storage,

Rainharvesting All

costs exclude

8-15 000 P / d reticulation

arid p u r i f i c a t i o n .

allowed f o r handpumps a n d r a i n h a r v e s t i n g .

No

conveyance

scale

pipe

cost was

233 WATER QUALITY It

is

purposes

use

having

water

without

no

paying

attention

supply to

for the

drinking water

sources of water can be dangerously p o l l u t e d , water

supply

needs

to

analyze

the

a n d the

water

and

p u r i f i c a t i o n systems. Where the p u r i f i c a t i o n i s not a l t e r n a t i v e sources must be sought.

and

other

quality

as

domestic

well.

investigation

install

Many into

appropriate

l i k e l y to work,

reliable

The f o l l o w i n g sources of p o l l u t i o n h a v e

to b e considered. Stagnant water:

could also be used f o r

to be severely contaminated w i t h

washing a b l u t i o n s etc.

and likely

b i o l o g i c a l matter, p a r a s i t e s .

Ground water: c o u l d be p o l l u t e d b y p i t l a t r i n e s ,

human o r stock p o l l u t i o n ,

dangerous n i t r a t e s a n d b a c t e r i a . R i v e r water: often s i l t laden especially d u r i n g flood; filtration. Rain

requires s e t t l i n g and

Could be Contaminated b y upstream i n d u s t r y .

water:

Dust,

nitrates,

sulphates

possible,

depending

on

wind

and

industry. Low cost advantage

filters of

are

frequently

removing

bacteria

used. as

Slow well

Disinfection should be considered, however, and chlorine chlorine.

pills,

or

sodium

hypochlorite

F l u o r i d e i s d i f f i c u l t to control,

gravity as

filters

suspended

have

the

particles.

i f there i s danger of b a c t e r i a , may

be

less

dangerous

than

a n d i t s use i s not recommended.

REFERENCES Abbott, J., 1988. R u r a l Water Supply. C o n t i n u i n g E n g i n e e r i n g Education. A Course on Water Resources i n Developing Areas. U n i v e r s i t y of the W itwatersrand. Economic Commission f o r I-atin America, 1973. P o p u l a r p a r t i c i p a t i o n i n development i n Comrnuni t y Development Journal ( O x f o r d ) , Vol. 8 , No. 3. M.B. Consulting, 1987. V i l l a g e water s u p p l y management handbook ( A r e p o r t pub1 ished for USAID, Maseru). Oakley. P. a n d Marsden, D., 1984. Approaches to p a r t i c i p a t i o n i n r u r a l development (I.L.0.). Stephenson, D., 1984. Pipeflow Analysis. Elsavier, 204 p . a n d Cohen, J . , 1979. F e a s i b i l i t y a n d a p p l i c a t i o n of r u r a l Uphoff, N.R. A state of the art paper (Ccrnell development participation: U n i v e r s i t y 1. WHO, 1982. A c t i v i t i e s of the World Health O r g a n i z a t i o n i n promoting community involvement f o r h e a l t h development (Geneva).