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					Safe Drinking Water The need, the problem, solutions and an action plan

Executive Summary Drinking water is the birthright of humankind. However, safe drinking water is denied to the majority of the world's population. This is certainly true in most parts of Africa and Asia. Even in relatively advanced countries such as India, safe drinking water is not readily available, especially in the rural areas. Here, the concern is not about any water (for other use) but about potable water, which can be consumed safely by human beings. Safe drinking water is a paramount requirement because 75 per cent of diseases in developing countries arise from polluted drinking water. It is high time that we bring about public awareness about safe drinking water. The knowledge of how to make water safe for consumption is not readily available to people in most developing countries. There are several good and simple scientific methods to purify polluted water to make it safe from drinking. This document describes some of the best ways available for purifying water by inexpensive methods, involving membranes, surface active materials and so on. Based on the local needs situations, appropriate methods can be employed to obtain safe drinking water in the different parts of the developing world. To this end, we hope this document will be useful. Besides this document, we propose to prepare a simplified version in the form of a poster or a pamphlet. These publications will be advertised through scientific academies and other organizations in various developing countries. Each developing country could produce suitable in local and national languages, and employ various other ways of reaching the common people for using these simple techniques. If we arouse the interest of all concerned, we may indeed make progress in solving one of the worst problems afflicting mankind.

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1.

Availability of freshwater Drinking water is the birthright of humankind, just as much a birthright as clean air is.

However, safe drinking water is not available to the majority of the world's population. Of the six billion people on earth, over a billion (one in six) lack access to clean drinking water. About two and a half billion (more than one in three) do not have adequate sanitation services. Together, these lead to water-borne diseases that kill over six million children every year (that is about 20,000 children every day). Ironically, water covers 70% of the globe's surface, but most of it is salt water that fills the oceans. The amount of fresh water that covers the earth is but 3%. Much of this lies frozen in the Antarctica and Greenland polar ice and thus unavailable. What is available for the use of humankind as freshwater comes from rivers, lakes and as underground water sources or aquifers, and all this put together comes to just about 1% of all the water on earth. Six billion people depend on this supply and a significant portion of these face shortage. Today 31 countries representing 2.8 billion people, China, India, Kenya, Ethiopia, Nigeria, Peru and others already face chronic water problem. As the population of the world rises to 8 billion in a generation, the amount of water is not going to grow. We need to find new and equitable ways of saving, using and recycling the water that is available to us. Figure 1 shows the water availability map of the world in the year 2025.

Fig 1

While the situation is grim, several things can be done to mitigate or eliminate the problem. Interestingly, the problem is not lack of water; indeed there is plentiful availability of freshwater resources in Latin America, the Caribbean, sub-Saharan Africa, and in Europe and Central Asia. Freshwater resources refer to total renewable resources such as river flow, ground water and rainfall. Water resources do not correlate with the economic level of countries. The Congo Republic, a developing country, has huge freshwater resources of the order of 291,000 cubic metres per capita, and Papua New Guinea has 170,000 cubic metres per capita, while the USA has but 9000 and Kuwait hardly has 75 cubic metres.

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Unequal access to safe water Access to safe water, however, varies between nations, and even within a given nation between urban and rural regions. For example, 77% of the people in the cities and towns of the Congo Republic have access to safe drinking water, but only 17% of villagers are similarly fortunate. Curiously, the situation is just the opposite in the Lao Peoples' Democratic Republic; access to safe drinking water is essentially 100% to the rural Laotian, while only 60% of those living in the capital city Vientiane are likewise blessed. The use of freshwater resources varies from one country to another. Among low-income countries, almost 90% of freshwater is used for agriculture, 8% for industrial purposes and only 5% is made available for household uses. In the high-income countries, it is industry that is the main user (59%), followed by agriculture (30%), and domestic use accounts for 11%. Given this scene, two factors raise concern about the availability of freshwater, and more particularly adequate safe drinking water, to the people of the world. One is that the total withdrawals of freshwater have increased steeply in recent times (doubled during the last 40 years). Ground water aquifers are being pumped down faster than they are replenished in parts of India, China, US and elsewhere. Improper and wasteful irrigation practices degrade soil quality and reduce farm productivity, threatening the 'green revolution' in food. Together, these have led to a decline in the amount and the quality of some freshwater resources. The second factor is the progressive rise in the population in various parts of the world, particularly in developing countries. When the population increases by 1.5 billion more by the year 2025, the per capita availability of freshwater is estimated to drop from the present global average of over 8000 cubic metres per year per person to about 5000, that is about 40%.

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Ways to save and replenish freshwater In effect, what needs to be done is to find ways to meet demands with fewer resources,

minimum ecological disruption and less money. Analysis of the situation suggests that these can indeed be done. Experts have suggested a five-fold path towards a viable solution - namely (i) seek new sources, (ii) save and redistribute supplies, (iii) reduce demand, (iv) recycle and (v) make it safe and potable. Some of these approaches are global while others will be region,

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country, and community and family-specific. And these will succeed when we empower people with appropriate means to do so.

Seek new sources

As we seek new sources, we note that extracting freshwater from the salty oceans is a time-honoured technique that can gather momentum with the development of new, energyefficient methods of desalting seawater. The earlier methods of heating and evaporating seawater, condensing and collecting the resulting freshwater is too expensive to be of universal use. The alternate, much cheaper and energy efficient technology is reverse osmosis. In this method, a thin, semi-permeable membrane is placed between a container of salty water and a container of freshwater. High pressure is applied to the water on the salty side, pushing the water molecules to cross over to the fresh water container. The material making up the membrane selectively allows water to cross, and keeps the salt and impurities off. The development of sturdy, chemicalresistant membranes (thin, composite polyamide films) that can be used up to 10 years, has made reverse osmosis technology an increasingly attractive and cost-effective method for large scale extraction of fresh water from the seas. Today, less than 1% of the world's drinking water comes from the sea, but with the advances in reverse osmosis, this proportion will grow.

Save and redistribute

The second path is to save and redistribute the supplies of water in a manner that it reaches the needy in a waste-free and inexpensive manner. This mode does not look to new sources but saves on existing ones. The simple act of plugging leaks from tankers, pipelines and taps alone will make a surprisingly large amount of water available. As the water expert Dr Peter Gleick of Oakland, California, has estimated, the water lost from the leaky supply system of Mexico City (population 17 million) is enough to meet the needs of a city the size of Rome (3 million people)! In many countries, more than 30% of the domestic water supply is lost because of leaky pipes, faulty equipment or poorly maintained distribution systems. Periodic repair and upgrading of these systems, plus small modifications in domestic facilities that use water (e.g. reduced volume flush toilets) can save substantial amount of water, making it available for redistribution to other needs.

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The act of harvesting rainwater has been practised by many communities for many centuries around the world. This practice has been on the wane in recent years for a variety of reasons, a main reason being the crowding into slums, tenements, apartment blocks and group housing. With the crunch in water supply, this time-tested and successful method needs to be revived and encouraged strongly. Many nations have indeed done so, with great success. Some of these case studies, detailed below, point to one of the most eco-friendly, easy-in-effort and energy-undemanding methods of catering to the safe water needs of large populations. Reduce demand The third path is to reduce demand. The main demand for water in developing countries comes from agriculture (74-78%) while developed countries use 60% of their water towards industrial needs. Domestic needs account for no more than 13% of the total water withdrawn in any nation. Reduction in demand must thus come from the farm sector and the industrial sector. Happily enough, newer and water-efficient processes have developed over the last 50 years; the amount of water used in the production of one tone of steel has come down sharply from the earlier 80 tons to the current level of six tons. Replacing steel with aluminium, other alloys and plastics (as in the automobile and transport industry) has reduced the need for water even further. Traditional agricultural practices the world over, particularly of rice and wheat, have been water-guzzling. Even minor improvements in agricultural efficiency will reduce demand on water, without in any way affecting the quality or yield of produce. Here again, several innovative methods, practised in many countries and discussed below, can easily be emulated by others.

Recycle

The fourth is to recycle the water and not let it drain off after a single use. The simple dictum here is 'waste not, want not'. Terrace farming, practised in many hilly communities and countries, is perhaps the simplest example, where water flowing from upper levels is not just drained but used to irrigate plants in lower rungs of the terrace. Even wastewater or sewerage can be, and has been, processed and recycled for use. The reed-bed system (RBS, see Figure 2) has

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been found, in many countries to be an eco-friendly way of treating polluted wastewater for reuse. Countries such as Israel, Namibia, India and Singapore practise recycling to great advantage. It is to be noted that even if it turns out to be difficult to recycle to great advantage. It is to be noted that even if it turns out to be difficult to recycle wastewater, it can be used to recharge ground water. It will help keep the ingression of salinity, improve the level of the water table in aquifers, and help create wetlands or sanctuaries.

Fig 2

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Making water safe and potable We now come to the ultimate path, namely to make the water obtained by the above means safe and potable. Making water safe for drinking has to be the very first priority for every nation on the globe, since today contaminated water kills more people everyday than cancer, AIDS, wars or accidents. It is thus vital that the water made available for humans to drink be free of disease-causing germs, and materials toxic to human health. Considering that over 80% of the people in the world are from developing and poor countries, the methods used to treat water and make it safe for drinking must be accessible and affordable to all, as well as culturally and environmentally acceptable. These methods will necessarily be of two kinds - ones that are used by the municipal authorities at central points from where water is distributed, and ones that can be practised in individual homes. The most common and effective methods to purify water for distribution is chlorination. Even in condition of very poor sanitation and hygiene, where people collect whatever water is available to use for their homes (such as community tanks, wells, pumps and taps), if the water is chlorinated, the incidence of water-borne diseases drops dramatically. The island cluster nation, Maldives, in the Arabian Sea/Indian Ocean, is an outstanding example in this connection. And an effective and inexpensive method for making water safe for drinking, which can be practised at home is the solar water disinfection technique (or SODIS) which uses sunlight and plastic containers to kill pathogens contaminating domestic water. There are over a dozen methods available, invented and practised by cities, communities and families in diverse parts of the globe, and a given family, village, community or settlement can choose the one that is geographically suitable, economical and culturally acceptable.

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Simple ways to obtain water: Some successful national examples Seeking new sources of water tend to be large-scale efforts, and involve large sums of

money. This effort will thus necessarily be at the national, or trans-national level. However, there are methods that can be put into practice quite effectively at the family and local levels, which bring in a rich supply of substantially clean water with little effort. Many countries have shown us the ways to do so. The commonest among these is water-harvesting, and involves capturing rainwater and use it both to recharge ground water and as ready reservoirs or collection ponds.

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Nepal: the small Himalayan nation Nepal has always had a water problem. Its population lives in far-flung communities, at places that are isolated, in hills of varying altitudes and where rainfall is restricted to 3 months of the year. Pipeline water supply is thus neither easy nor viable. The Nepalese have thus found innovative microlevel methods to capture and harvest rainwater at rooftops, soak pits and village- and district-level ponds. The community-based rainwater harvesting scheme called Baresiko Pani Thapne has been working in several districts of this country, easing the water problem in an economical efficient and empowering manner, with people's participation. Sri Lanka: This pearl on the Indian ocean has a long-standing tradition of harvesting rainwater using palm leaves, tree trunks and rocks. Water is captured from rooftops through a variety of gutters, ranging from tin sheets to split bamboo, banana stem files or arecanut sheaths. Experiences in the Anuradhapura District indicate that householders collect rainwater more for its better quality than anything else! It is well to remind ourselves that rainwater, particularly after the first showers, is distilled and condensed and thus comparable to reverse-osmosis water, or to the bottled water sold by manufacturers for a price. Kenya: This lush equatorial country of great geographic contrasts has a national level rainwater association. In Laikipia, they started harvesting rain in 200-litre drums, and moved on to large 50-100 cubic metre (megalitre) drums. This amount proved ample for human and livestock needs as well as for small-scale vegetable cultivation. This, coupled with runoff farming for terraced agriculture, has helped in increasing the efficiency of water harvesting. Notably, all these advances have happened within 10 years, making a big difference in agricultural productivity and standard of living. Ghana: The Ghana Water and Sewerage Corporation (GWSC), established in 1965, works along with non-governmental organizations (NGO), individuals and communities, and provides safe, potable water through ground water and surface water sources. The methods used are comprehensive, and similar to those in Kenya. The National Water Supply Programme of the GWSC provides water to about 60% of its 56000 rural communities through such efforts. Indonesia: Dean Desa, a non-government organization in this archipalego nation, has an innovative method to entice and encourage people's participation in water economy. They build rainwater storage cisterns, for which the former has to repay the loan cost. Two female goats are

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given to his family. When they bear four young one (which is usual), two of these are returned to the owner and the other two go to the borrower. The borrower rears them and uses them as payment for the water tanks. Taking a leaf from this, Phillipines has put this idea into practice, but the mode of repayment here is hogs rather than goats! Singapore: This tiny nation offers the most comprehensive and multipronged example of capturing rainwater and putting it to human use. It is a well-planned, easy-to-execute, costeffective and essentially permanent solution to a vital problem facing many cities or "concrete jungles". Every high-rise building in the city has to provide rooftop collection systems, from where the collected water is sent to two tanks, one of which is used only for toilet flushing. The attendant perennial problem of mosquitoes is taken care of through fine mesh screens covering the tanks, and by docesing the stored water with a paraffin oil layer. In addition to apartment houses and high-rises, all educational institutions are also required to collect roof top rain water and run it off to chambers for sedimentation and chlorination. Another huge catchment area is the airport. Runoff from building roofs, runway and related turfs of Changi Airport is able to provide as much as 80,000 cubic metres of water. Detailed analysis of the benefits, using computer programmes, indicates an effective saving of over 14%, and that the cost of the rainwater is close to 25% cheaper than potable water. India: Perhaps the most dramatically successful (and hence often in the news) effort in harvesting water and using it for community farming and domestic needs is that in the sprawling desert province of India called Rajasthan. We highlight it here because of two reasons. One is that many areas in Central and West Asia, and Saharan Africa have remarkably similar geo-climatic situations and the experience in Rajasthan are relevant and replicable. The second is that it is an example where the "technical solution of an urban engineer", namely dig deeper borewells and fit handpumps has been successfully replaced by the 'commonsense' and rural wisdom of the participant people with the attendant cultural/sociological angles built in. as many as 154 remote rural schools and 53 community centres located in dry or brackish water areas were recruited by non-governmental agencies, and after considerable interactions with and input from the villagers, 207 underground tanks were constructed. These involved local materials, local masons and local labour, giving employment to 6000 people and over a decade, gave 12 million litres of collected rainwater. There has been very little subsequent maintenance problems, the kind that plague

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handpumps and piped water. And, what the handpumps (unintentionally) cut off was restored with these tanks and wells - namely the use of the open village well as meeting point of rural women who went there to bond with one another, exchange information, news and gossip, and for rest, recreation and time off from their men and families! Plus, tans do not drain or lower aquifer levels. In the eastern part of Rajasthan, a rain-fed land, a NGO called Tarun Bharat Sangh (TBS) has helped the local people build 4500 check-dams and water-harvest-structures in 850 villages, using local money, labor and planning. This has helped over 100,000 people with agriculture, raise water levels in wells by 2-3 metres and turn seasonal rivulets and tributaries into perennials. Their leader, Rajendra Singh, was the winner of the Ramon Magsaysay Award for the year 2000. 4. Making wastewater fit for use again The above national examples describe effective methods of harvesting water and improving the aquifer levels, so that groundwater recharging becomes possible. Has this not been done, an important source of available water would have been wasted. Another source which need not be discussed as waster, but can be recycled and made fit for consumption, is wastewater. If left unrecycled, wastewater of course returns to the earth (directly or after evaporation). The pollutants in it are however, not recovered, controlled or treated, thereby polluting the location where it is discharged. Recycling wastewater involves the removal (and recovery if needed) of the pollutants as well. Two pilot examples from Sri Lanka and Chile are worthy of further development and emulation. The Sri Lankan Experiment: Sri Lankan produces raw rubber and processes if to value-added products. In addition, this nation also has vibrant coconut and textile product sectors. Together, they generated considerable wastewater as effluents which can be treated and made usable again. To this end, the Rubber Research Institute put up a pilot plant to treat the daily output of 30 cubic metres (30 million litres) of effluent water. The system consists of (i) an initial particular matter trap, consisting of 4 compartments that lengthen the pathway in stay time; (ii) following which is an anaerobic digestion chamber, with five compartments that hold and handle two days'-worth of effluent in an innovative rectangular tank with a single small vent. Anerobic bacteria fixed as colonies in rubberised coconut fibres that fill the tank, convert the dissolved organic pollutants into gas (methane, hydrogen sulfide, carbon-dioxide - 40 cubic metres of gas per 2 tons of rubber

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per day); (iii) the outflow now comes to aerobic tank, where the biodegradable pollutants are digested in the presence of bubbled air; (iv) the aerobically treated effluent is fed into a circular conical floored clarifier, so that solids settle into a sludge in the bottom and the effluent flows out of the clarifier's water surface into (v) a sand-bed filter. Sand is packed at the top, followed downwards by 'metal' gravel and stones of increasing size. The filtered liquid is now discharged for reuse. Three such plants are in operation since 1995, and the process is licensed to a commercial firm for marketing. The experiment at Chile: The scale of operation and the methods used here are different from those in Sri Lanka, making this more suitable for sewerage from human settlements rather than industrial effluents. This is a totally aerobic process, consisting of two steps. The first phase uses a biofilter through which the wastewater is drained. This filter consists of several layers - bottom most are stones, above which are smaller stones and gravel, a layer of sawdust, and on the top, 20-30 centimeters of humus containing a large number of micro-organisms and 5000-10,000 earthworms per square metre. The wastewater that has passed through this biofilter is clear, with its original organic content drastically reduced. Since the process is aerobic, the larger the area and greater the aeration, the better the effectiveness. In the second stage, water is processed through a shallow chamber where it is irradiated with ultraviolet (UV) radiation from a UV-lamp delivering 30 watts per square meter per second. This intensity of UV kills all bacteria in the water within a minute. The water that comes out of the UV chamber is excellent and sterile. This Chilean bio-reactor can handle up to 1000 litres a day per square metre. The system is easy to maintain. Residues do not accumulate. The only regular maintenance needed is to add sawdust to the biofilter every few months. Some of the humus should be removed during the course of a year to maintain an active, growing biosystem. The electrical consumption is not much either. The system is now patented and commercially installed at various localities in Chile - for settlements of 500 and 1000 peoples, schools, a region of 12,000 people and so forth. Private Industry Initiative: In addition to the national initiatives, efforts have been financed and implemented by private industry (e.g. Unilever) on a apprehensive and international basis to save and rechange lakes, recycle water through a variety of means, and to make potable water available to villages (e.g. the PAGER programme of Unilever in Morocco). The American initiative from 'Plebys' likewise has developed a simple two-stage filter (somewhat similar to the Chilean type), which can be used quite easily at home. These programmes have woven into them active community participation and even financial contribution (a few cents a day to pay for the

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cost of the materials and water supply). Such people - NGO collaborations have used locally available talent, resources and organizations in order to make water available on a safe and steady basis. 5. Technologies to make safe drinking water Finding ways to make water available through the various methods described above is to have won half the battle. The next challenge is to make this water safe for drinking. Unless this is ensured, we will not have won the war against water-borne diseases and eliminated the avoidable mortalities and morbidities. Over the years, several convenient and easy-to-use methods have been suggested; some of these involve high-technology based, which are more suitable for use at the city/central point of treatment for subsequent distribution. Some others can be used at the settlement cluster level, e.g., apartment buildings, village groups, schools and community centres. And there are "low-tech" or appropriate-technology level methods that can be used in individual homes, or during situations of emergency or urgency. It is important to note that the quality of water obtained by any of these techniques - high-tech, medium-tech or traditional and appropriate-tech-is excellent, free from pathogens and toxins and as fit for drinking as the water sold in sterile bottles as 'purified drinking water' or mineral water (with or without gas). 5.1 High-tech / high volume methods:

The time-honoured and certified methods of treating high volumes of water (catering to a citysized population) involve initial sedimentation and filtration followed by the killing of pathogens by chlorination (or in some cases ozone bubbling). While this is still logistically possible and quite acceptable for relatively smaller volume demands (village clusters, schools and dormitories, hospitals and so forth), the methods adopted in these instances have to contend with not a static, captive pool of many cubic metres of water, but a "flow through" or steady-state volume of water, but a "flow through" or steady-state volume of water collected in a siphoned tank. The volumes involved may be several cubic metres (megalitres) at any given time. There are several methods that have been suggested and tried out with success. We highlight a few of these below. (a) UV-protected granulated activated charcoal bed for water treatment: This innovative apparatus has been developed at the NASA Johnson Space Center of USA. Charcoal has been a very attractive and effective material to purify water,

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since it is able to effectively adhere to (absorb on its surface) diverse classes of contaminants, inorganic, organic and biological. The larger the surface area of the charcoal the more effective it is in doing so, and hence the use of powdered or granulated charcoal rather than lumps. The NASA process extends the active life of the charcoal (hence longer time of use of the same charcoal bed before it needs to be replaced) by the use of ultraviolet light, which inhibits the growth of microbes on the carbon surface and disinfects and purifies the water passing through the Teflon tubing. Benefits of this technology are that it uses UV light rather than chlorine, which may leave residuals, and the UV also prolongs the lip of the active charcoal bed and sterilizes it. (Further details may be obtained on the Internet at the website www.usrttc.org/PDF/TBQ298.pdf (b) Titanium dioxide and UV light as the purifier: Over 20 years ago, Japanese scientists showed that the naturally occurring mineral called anatase (a form of titanium dioxide or TiO2) is a very efficient disinfectant, when irradiated with ultraviolet radiation. When UV light is shone on it, TiO2 produces reactive oxygen species and free radicals, which kill bacteria, fungi and viruses effectively in a very short time. TiO2 is a mineral that is abundant in nature (found in Africa, Australia, Sweden and Canada in the purest raw form), and has been used as a whitener in paints, toothpastes, cosmetics, paper and other material. The addition of TiO2 to water at the treatment level and shining ultraviolet rays on it (quite like the Chilean experience quoted above) purifies the water though "photocatalysis" (photo, since UV light is used and catalysis because the TiO2 is not used up; it only aids the purification and does not get consumed). About 10 years ago, the first International Conference on TiO2 Photocatalytic Purification and Treatment of Water and Air was held in Canada. This highlighted the benefits of using TiO2 and UV-light in purifying water by oxidizing pollutants, destroying toxins and pathogenic microbes present in water. In TiO2, thus we have an abundant and costeffective water purifier. Since the Canada conference, several improvements have been made to the TiO2 photocatalysis method, making it simpler and more general. We discuss two such improvements below. (c) TiO2 and sunlight to purify water: TiO2 is an inexpensive and non-toxic substance for the purpose of water purification. It has, however, too disadvantages.

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One is that it is suspended in the powder form and must subsequently be filtered out of the water. The second is the need to use ultraviolet light (below 390 nanometres), while most of the sun's light that falls on earth is above this, and in the visible range. In order to solve both these drawbacks, a team in Germany first immobolized the catalyst as coatings on glass, using a process (sol-gel transformation) that produces solids from liquid solutions. These coatings can be used with the same effect and for longer periods, with no need for filtering. Then they improved the light absorption character of by TiO2 adding small quantities of iron oxide (Fe2O3) into the TiO2 grid. This allowed the use of direct sunlight rather than UV-light. In experimental tests, the composite TiO2 : Fe2O3 catalyst coated on glass, and the use of sunlight, proved successful. This improved method appears to be much broader use. (Further information can be had at hopp@isc.fgh.de. (d) Electrochemical activation (ECA) method: Here electrical energy is used rather than light for purification. The catalyst is not TiO2 or (TiO2 Fe2O3) alone, but a mixture of oxides of various metals (Ru, Ir, Pt, Ti….) which are coated on the surface of electrodes. The electrodes are placed on either side of a vessel that is divided into two sections by a vertical diaphragm (ceramic, coated with other oxides) that separates the water contained in the two chambers sandwiching it. Rain water is passed through one of these anode chambers and exits from thee into a second vertical chamber that contains catalyst granules (replacement-free and regeneration-free) which oxidizes all organic and biological substances and decontaminates the water. The outflow is fed into the other chamber of the electrolytic column, while a direct current electrical energy is passed using a car battery. The design of the electrolytic reactor is such that electrochemical activation (double layer intensification) is too intense as to purify even the most obdurate pollutant. The ECA purifier has been commercialised as Aquastel by a group from Estonia, and is suggested to be a low cost, easy-maintenance, purification device that provides drinking water of WHO standard-quality to small communities. Its yield is 120 litres/h, cartridge replacement essentially unnecessary for years and needs little energy. (Details at www.aquastel.com/summary.html). (e) Portable reverse osmosis water purifiers: Many commercial companies now make small, home-use reverse osmosis devices that can produce regularly 7-

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litre/hour supply of pure water, from any type of input water. They can be mounted on the wall, consume very little electricity to operate, use membranes that do not need replacement for 2-3 years, and filters that need to be replaced only yearly. The cost of such home units has also come down, and currently are available for about US$ 200. Larger units that can serve a whole apartment building, with throughput rates of 100 litre/hour are available, for about US$ 4000. These appear attractive for home or community use in places where water is hard or brackish, but for middle and higher income groups. (f) Efficient adsorbent filters: Filtering water removes suspended particulate matter. The finer the filter, the more it can decontaminate and purify. The use of a membrane allows selective passage of the water while preventing chosen dissolved material from passing through. The need in water purification is a quick-flow, corrosion-resistant, high-stability (towards pressure, temperature and contaminants) bactericidal and economical membrane filters. Recent work in Russia on what are called SHS filters appear promising, since they satisfy the above requirements well and are also economical. They appear suitable for domestic community and industrial uses (Details may be had by writing to head@ism.ac.ru).

5.2

Appropriate technology methods for home use: In isolated communities, rural villages of developing nations, and during times of immediate needs or emergency, access to low-level, and quick but reliable methods for purifying small volumes of water (10-1000 litres) should be available. And these should be, as far as possible from materials available in the neighbourhood. The use of alum, permanganate and chlorine tablets for quick purification is easy and practicable at the domestic level, and during camps. A well-known and safe method practised at homes in South Asia involves a two mud-pot filtering system (Figure 3).

Fig 3

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The top pot contains pre-washed gravel and sand through which raw water is passed. It exists through a hole in the bottom of this pot into a second collection pot kept below. This pot contains a cloth filter at its mouth and a crushed coal bed on a suitable pad. This serves to remove many toxins and germs from the input water. The so cleaned water now exists through a hole in the bottom of this second pot and is collected below in a third earthenware pot. The collection rate is slow, but the home-maker plans the collection overnight so that clean, cool drinking water is available throughout the day. This method requires no electric power, no filters to buy, no chemicals and no maintenance cost, but the charcoal, gravel and sand need to be replaced every few days. A very easy, small scale, and cost-effective technique for providing safe water, at homes or in small communities is the highly effective solar disinfection (or SODIS) method. In this method, water is first filtered to remove solids and particulate matter. Then it is taken into a throw-away, colourless, transparent bottle and kept out in the sun for irradiation. It is best to lay the bottle flat on the ground and to blacken the bottom surface so as to collect the light and heat better (Figure 4). The solar radiation and heat inactivate the pathogens in the water. The treated water can now be stored in a cool mud pot for drinking (for further details, check in wegelin@eawag.ch). This method has been tested in Bolivia, Burkina Faso, China, Colombia, Indonesia, Thailand and Togo, and found to work very well.

Fig 4

In places where electric supply is available, filter cartridges (with or without irradiation) can be used either on the stored supply or the flow-through supply. 6. Action Plan It is clear that the situation with regard to availability of safe water for homes and communities is not as grim as has been though with efforts from the community, townships, state, governments and NGO, and international cooperation, safe water for the world is a realizable goal. This has been the theme of the Africa 2000 Initiative for Water Supply and Sanitation, launched by WHO in 1993, resulting in the Brazzaville Declaration

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1996 which set out relevant principles and Kay recommendations to enable the people of Africa to have access to safe water supply and sanitary waste disposal facilities. 6.1 Individuals and Communities Efforts need not be left to the governmental and nongovernmental agencies. Individuals, families and communities have a vital role to play. Towards achieving their birth-right of safe drinking water, they too have various acts and to perform. These include the following: (a) Water harvesting at the house, apartment block, schools and community buildings, (b) Recycling water at the microlevel - including home, building and street sewerage levels. (c) Saving water by ensuring taps, and pipes are not leaky and by using just optimum amounts for washing, toilet flushing, and similar purposes. (d) Making sure that the water is purified by one of the methods, suited to the family conditions and needs, before using it for drinking (boiling the water where possible!), and (e) Maintaining proper levels of sanitation at home and around.

6.2

Governments As the Second Regional Meeting on the Africa 2000 Initiative, held in Harare, Zimbabwe, a framework for action was listed, along with a series of recommendations. While these were directed towards African nations, these recommendations and action plan are relevant for much of the world. Based on these and similar deliberations elsewhere, and on the material discussed above, we suggest below an Action Plan. The objectives of the Plan are to (i) assist countries in the formulation, implementation and monitoring of policies and strategies for programmes of safe water supply, and (ii) to promote cooperation among governments, international agencies, support organizations, NGOs, and the private sector for water supply and sanitation. The major concerns involve: Community Empowerment and Management, Private Sector Involvement in Water Supply and Sanitation, Country Level Collaboration and Cooperation, and

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Sanitation and Hygiene Education for Health Improvement. The action point issues are as follows: (a) Political commitment. This should translate through policy formulation, support for the implementation of the plans, and improve budgetary allocation towards these. To do so, identification of committed and well-recognized government functionary to mobilize public awareness and a campaign aimed at the stockholders and allocation of appropriate funding is essential. (b) Inter-sectoral coordination and cooperation, in order that a consensus and coordinated programme is arrived at, roles of individual sectors defined and resources are pooled such that the ultimate goal of reaching safe water to the families is achieved. (c) Support to local efforts and community approaches, so that self-improvement of communities is enabled and community management is promoted. (d) Facilitate access to appropriate technologies. (e) Institute legal and regulatory framework for private industry and NGO participation in the efforts. (f) Promote mechanisms that enable government structures to perceive and act on sanitation as a national priority. This would take the form of activities such as develop specific sanitation policies and guidelines, organize advocacy campaigns targeting policy makers, and integrate hygiene education in all water supply and sanitation projects. (g) Involvement of women in water supply activities, through the identification of existing women's movements and groups at all levels, and also create or incorporate associated women's groups in community level activities of water harvesting, recycling, saving and purifying, and supply.

6.3

Private Industry and NGOs Many countries have active and successful NGOs that have involved the communities in a

fund, share and work mode that has transformed arid and semiarid terrains into agricultural level (India, Indonesia, Kenya, Nepal) and water-adequate.

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These need to be funded by banks and foundations and coordinate their efforts among themselves. Action points in this connection would be as follows:

(a) Exchange information among and between themselves about relevant and novel methods and strategies used. (b) Pay attention to sociological factors that may have a say on the technical solution and choose methods that are most suitable to a given region/community. (c) Attempt to ensure equity in the service provided and the benefits that result. (d) Involve themselves in all aspects of water supply-saving run-offs, harvesting, recycling, storage, purification and supply, and (e) Coordinate efforts with those of the governmental and intergovernmental sectors towards a harmonious end-result.

Ultimately, the proverbs "waste not, want not", "little drops of water make the mighty ocean" and "what is saved is what is earned" represent simple truths. Water is available in plenty; what is needed is to ensure that it is not wasted but treated, purified and made available in plenty; what is needed is to ensure that it is not wasted but treated, purified and made available in a fair and safe manner. The task is do-able; thanks to the way the hydrological cycle operates on earth. The earth does not let a drop of water escape but wraps it tightly within and around itself. We who live on earth can do so too.

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Description: Safe Drinking Water