26-04-2012, 11:15 AM
Guidelines for drinking-water quality
Guidelines for Drinking-water WHO.PDF (Size: 3.6 MB / Downloads: 37)
Introduction
Scope and purpose
This volume of Guidelines for drinking-water quality describes the methods employed
in the surveillance of drinking-water quality in the light of the special
problems of small-community supplies, particularly those of developing countries,
and outlines the strategies necessary to ensure that surveillance is effective.
It is also concerned with the linkage between surveillance and remedial action and
with the form that remedial action should take.
The structure of this volume reflects the key stages in the development of
surveillance, as summarized in Fig. 1.1. Thus Chapter 2 covers planning, and
subsequent chapters deal with the procedures used in the collection of information—
sanitary inspection and community surveys (Chapter 3), and the analysis
of water quality (Chapter 4). Chapter 5 considers the analysis and interpretation
of the information gathered and its use in improving water-supply services. The
final three chapters cover strategies for improvement—technical interventions
(Chapter 6), hygiene education (Chapter 7) and legislation and regulation (Chapter
8).
Community water supplies
The precise definition of a “community water supply” will vary. While a definition
based on population size or the type of supply may be appropriate under
many conditions, it is often administration and management that set community
supplies apart, and this is especially true in developing countries. The increased
involvement of ordinary, often untrained and sometimes unpaid, community
members in the administration and operation of water-supply systems is characteristic
of small communities; this provides a ready distinction between community
water supplies and the supply systems of major towns and cities. However,
water supplies in periurban areas—the communities surrounding major towns
and cities—are often organizationally similar to those of rural communities; these
may also be classified as “community water supplies” and are therefore included
in this volume.
Health implications
The provision of an adequate supply of safe water was one of the eight components
of primary health care identified by the International Conference on
Primary Health Care in Alma-Ata in 1978. The guidelines presented here are in
full accord with the spirit of the Alma-Ata declaration on primary health care,
which expanded the concept of health care to include broader notions of
affordability, accessibility, self-reliance, intersectoral collaboration, community
participation, sustainability and social justice.
Microbiological aspects
Ideally, drinking-water should not contain any microorganisms known to be
pathogenic—capable of causing disease—or any bacteria indicative of faecal
pollution. To ensure that a drinking-water supply satisfies these guidelines,
samples should be examined regularly. The detection of Escherichia coli provides
definite evidence of faecal pollution; in practice, the detection of thermotolerant
(faecal) coliform bacteria is an acceptable alternative.