Preface

Water is one of the basic necessities of life. Without one to two liters of water per day a human being cannot survive. And, to lead a minimal human existence, one needs between 20 and 50 liters of water per day for drinking, the preparation of food, and personal hygiene. For many people, this bare minimum is unattainable, because clean water is scarce.

Although two-thirds of the earth's surface is covered by water, only 0.8% is available for human beings to use - and even this small fraction is largely contaminated. More than half the population of the Third World have no adequate access to clean drinking water— three-quarters have no sanitary facilities.

The rural population is especially affected. Polluted water and fecal matter are the main factors responsible for the spread and transmission of infectious diseases in the Third World, some of the consequences of which are short life expectancies, high rates of infant mortality, high costs of medical care, and low productivity.

The United Nations have declared 1981 -1990 the International Decade of Water - the goal of which is to provide all of both the urban and rural populations with clean drinking water and adequate sanitary facilities within this time period, giving precedence to those areas most neglected -namely, rural areas and urban slums.

Table 1: Number of people in the Third World (mill.) without access to clean water and sanitation (excluding China); see [1, 2, 3].

	Total Population	Population without clean water	Population without sanitation
Urban	703	177 (25%)	331 (47%)
Rural	1612	1143 (71%)	1399 (87%)
Total	2315	1320 (57%)	1730 (75%)

Table 2: Percentage of Third World population sufficiently supplied with water (excluding China). In 1962, 67 countries were examined; in 1970: urban -97 countries, rural -90 countries, 1975: urban -79 countries; rural - 75 countries; 1980, 74 countries were examined [1, 2, 3].

Year	Urban Population		Total	Rural Population	Total
	House Connections	Public Standposts
1962	32	25	58	-	-
1970	50	17	67	14	29
1975	57	20	77	22	38
1980	-	-	75	29	43

To make a realistic attempt to reach this goal, considerable thought has been put into what technological level should be reached and the decision is to place increased emphasis on so-called "appropriate technologies." The meaning of that phrase is closely bound up with the situation of the location where it is to be considered.

Generally speaking, these technical methods and devices which come under consideration should:

- be compatible with the social, cultural and economic conditions of the target area;
- be comprehensible to the users so they can become familiar and habitual;
- exploit locally available resources;
- be labor-intensive, inexpensive, and simple to operate and maintain.

The concept "appropriate technology" does not imply modern or sophisticated technology versus basic technology, but, on the contrary, out of a wide spectrum of possible methods, materials and systems, a choice must be made that is specifically tailored to a particular place. In order to turn a technically reasonable program into reality, the essential ingredient is the motivation of the

political decision-makers who have to carry the financial burdens over an extended period of time and appoint the institutions responsible for the fulfillment of the project. To be successful, the program will, in its long-range planning, have to take personnel matters into account, next to financial and institutional aspects. Training of personnel at all levels, supporting health care and counseling programs must be included.

This manual covers an area hitherto neglected within the developmental aid projects that have sought to use appropriate technology for rural water supply and sanitation. The treatment of drinking water in these areas is generally viewed as too problematic to accomplish. But, as the study at the beginning of the International Decade of Water shows, the shortage of clean water hits the fringe areas of Third World countries the hardest. Hence, the attempt to treat the available contaminated water with the help of simple and safe methods must be considered a possible way of counteracting these conditions. For this attempt, we must review known methods to see how readily applicable they are.