Sourcebook of Alternative Technologies for Freshwater Augumentation in Small Island Developing States


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United Nations Environment Programme
Division of Technology, Industry and Economics

Newsletter and Technical Publications

PART B - ALTERNATIVE TECHNOLOGIES

1. TECHNOLOGIES GENERALLY APPLICABLE TO ISLAND STATES

1.4 Water Conservation

1.4.2 Water Conservation and Protection Measures

Water conservation covers a large number of different technologies. The water conservation measures that are most commonly used on small islands include leakage control; metering and pricing; and, use of water-saving devices. To be successful, these measures must be supported by the necessary policies and enforceable legislation. A high community involvement is also required, which necessitates an on-going public information programme on ways and means to conserve water.

Technical Description

Leakage can occur from pipes, valves, hydrants, fittings, and tanks within both community delivery systems and individual user systems (Figure 14). There are a number of methods of leak detection which include passive leakage control (detection by visual inspection only as is often done by the community); regular soundings (detection by systematic soundings at valves and other locations using special electronic devices); district metering (detection by metering and analysis of flows into various pre-determined districts over a period of time, followed by systematic soundings); waste metering (detection by metering of low flows at night from predetermined waste districts served by a single pipeline, followed by systematic soundings); and, combined district and waste metering. These measures may be used in combination. For example, if passive leakage control is undertaken, regular soundings, district metering and waste metering methods can further reduce leakage. An economic analysis is generally required to determine the most cost-effective method, but, ultimately, a balance between doing nothing and attempting to stop every leak must be achieved (UNESCO, 1991).

Figure 14. Amount of water lost due to small leakages.

Experience has shown that universal metering can have beneficial effects on water conservation. Metering includes installing bulk meters on the main distribution lines as well as on the individual household connections. Water pricing can be used not only to raise revenue but also to improve the efficiency of water use. The latter effect is an example of water conservation by demand management. When people have to pay for water they are more likely to conserve its use and minimize losses due to leaks. A simple method to determine if an individual metered system is leaking is to turn off all water taps and see if the meter indicates any flow. If it does, the system needs to be checked. In formulating a water pricing policy, a number of factors are important, including the capital and recurrent costs of treatment and distribution of water; the current level of government subsidy; the amount of any external (generally aid) funding; the types of water consumers (i.e., domestic, industrial, etc.) and relative levels of demand; and, the ability and willingness of the consumers to pay.

Given en economic incentive to conserve water, there are a number of water conserving devices that consumers can use. Dual flush toilet cisterns, which commonly have 5 l and 10 l capacities, can save up to 15 l/person/day. Other conservation devices include flow restricters on showers and taps, and spring-loaded taps on communal standpipes (although, in practice, these generally have higher maintenance requirements and costs and have been labelled as inappropriate technology for Pacific Island countries; WHO, 1989). Decisions about the use of water conserving devices should be made with a knowledge of local conditions and customs (UNESCO, 1991). For example, rather than installing taps, simple plastic handpumps are used in Tonga to withdraw water from partly buried rainwater storage tanks. The user pumps only as much water as s/he requires, and the use of a pump is consistent with local custom. However, the problems associated with leaking taps are overcome by using the handpump, and the rainwater tank set into the ground allows more fall in the gutters and pipework connecting the roof to the tank, and, thus, somewhat more water to be captured and stored.

Extent of Use

Leakage control is used widely in SIDS. In Seychelles, leakage detection programmes reduced the water losses from 40% of water supplied to 22%. The benefit:cost ratio of this programme in 1985 was estimated at approximately 5:1. Similarly, in the Bahamas in the late 1970s and early 1980s, leakage detection programmes reduced the water losses from 54% to below 40%. On Malta, leak detection methods reduced losses from 55% of water supplied in 1968 to 25% of water supplied in 1977. The expected benefits of $5 million per year far exceed the estimated costs of $300 000.

Metering and pricing is used by most larger public water supply systems in SIDS. A 43% reduction in consumption was attributed to metering in the Town of Honiara, Solomon Islands, while, in Pohnpei, Federated States of Micronesia, the introduction of metering and pricing resulted in a 25% reduction in the water consumption. In American Samoa, it was reported that upon installation of meters, metered domestic consumption decreased from between 380 and 570 l/person/day to approximately 230 l/person/d. In French Polynesia, the consumption of domestic water was cut by a factor of 4 in response to the metering of household distribution.

Water-saving appliances such as the dual flush toilet cisterns are used on a number of islands. However, such devices do not have universal application as not all islands or cultural groups have the basis for making use of such technologies.

Operation and Maintenance

Leakage-detection equipment needs to be maintained. Meters need to be tested regularly and, if necessary, repaired. The operation of a pricing system requires meter readers, and an appropriate billing and revenue collection system.

Level of Involvement

Leakage control requires trained technicians to conduct the leakage detection, and trained plumbers to repair the leaks. The maintenance of meters requires skilled technicians, although, if necessary, meter reading can be done at the community level.

Costs

The costs for leakage control comprise the purchase of equipment, the training of personnel, and the conducting of leakage studies. Leak detection may be done by the water utilities corporation as part of their general maintenance costs. Alternatively, consultants can be hired to perform leakage detection, but this latter option tends to be expensive and is generally non-sustainable.

The costs of consumer metering involve purchase and installation of the meters, the regular reading of the meters, and periodic billing and revenue accounting. The cost of the meters is in the range of $140 to $200 per domestic installation.

Effectiveness of the Technology

Leakage control is very effective as a water conservation measure. "Unaccounted-for" water can usually be reduced by up to 50%. The use of metering and water pricing will reduce water consumption by 25% to 30%, on average.

Suitability

These water conservation measures are suitable for all public water supply systems on small islands.

Advantages

The various water conservation measures discussed above have differing advantages (and disadvantages). Leakage control systems generally improve knowledge and administration of the water supply system, and provide for improved security of water quality due to fully pressurised pipes. Leakage detection also reduces the volume of unaccounted-for water by fixing leaks and locating illegal connections, both of which increase revenues and help to conserve available water resources. Metering and pricing policies help consumers become aware of their water consumption habits. Metering assists in the development of a pricing structure that is appropriate to the individual water supply system (i.e., providing rewards for conservation and penalties for wastage), while better enabling monitoring the overall water consumption. It also assists in pinpointing where leakage control programmes would be most beneficial. Both metering and pricing and the use of water-saving devices also help to conserve water.

Disadvantages

The disadvantages of these actions include the cost of implementing leakage control, metering and the use of water saving devices, and of maintaining the systems once they are in place. Metering is not generally popular with consumers and politicians.

Cultural Acceptability

Decisions on metering and pricing policies need to be made after consultation with local communities. In particular, the ability of consumers to pay needs to be assessed. Special measures to relieve the financial burden on particularly disadvantaged groups may need to be considered.

Further Development of the Technology

These water conservation technologies are all very well developed. However, it is necessary to continue to improve these methods to reduce the cost of implementing the technologies, and to reduce their capital, maintenance and administrative costs.

Information Sources

AGDASCG [Australian Government Department of Administrative Services Construction Group] 1987a. Operation and Maintenance Manual for Tarawa Water Supply System. Department of Administrative Services Construction Group, Canberra.

AGDASCG [Australian Government Department of Administrative Services Construction Group] 1987b. Tarawa Water Supply Project: Public Awareness Campaign. Department of Administrative Services Construction Group, Canberra.

American Water Works Association 1993. Manual of Water Supply Practices: Water Rates. AWWA, Denver.

American Water Works Association 1985. Economics of Leak Detection, A Case Study Approach. AWWA, Denver.

Bastemeyer, T.F. and J.T. Visscher 1987. Maintenance Systems for Rural Water Supplies. International Reference Centre for Community Water Supply and Sanitation Occasional Paper Series No. 8, The Hague.

Baudish, P. 1984. Conservation of Water Resources - a Look at Ways to Reduce Demand for Potable Water. Commonwealth Science Council Technical Publication No. 182, Part 3, 493-501.

Baumann, D.D., J.J. Boland, and J.H. Sims 1980. The Problem of Defining Water Conservation. The Cornett Papers, University of Victoria, Victoria, Canada. pp. 125-134.

Boland, J.J., B. Dziegielewski, D. Baumann, and E. Opitz 1984. Influence of Price and Rate Structures on Municipal and Industrial Water Use, US Army Corps of Engineers Institute for Water Resources Report 84-C-2, Fort Belvoir.

Brewster, M.R. 1989. Water Resources Management in Small Island Countries: Cost Recovery and Demand Management. In: Interregional Seminar on Water Resources Management Techniques for Small Island Countries. UNDTCD Report No. ISWSI/SEM/38, United Nations Development Programme, New York.

Cook, S.W. and J.L. Berrenberg 1981. Approaches to Encouraging Conservation Behaviour: A Review and Conceptual Framework. Journal of Social Issues, 37(2):73-107.

Depamelaere, R. 1986. Reduction of Unaccounted for Water in Water Supply Systems. Water Supply, 4(2):49-53.

Frederick, K.D. 1993. Balancing Water Demands with Supplies: The Role of Management in a World of Increasing Scarcity. World Bank Technical Paper No. 189, The World Bank, Washington.

Grisham, A. and W. Flemming 1989. Long Term Options for Municipal Water Conservation. Journal of the American Water Works Association, March.

Jessop, P.A. 1986. The Effectiveness of Leakage Control in Distribution Systems. Water Supply, 4(2):65-74.

Kearsey, J.R.M. 1986. Reduction of Unaccounted Water in Water Supply Systems. Water Supply, 4(2):55-64.

Lerner, D.N. 1986. Leaking Pipes Recharge Ground Water. Groundwater, 24(5):654-662.

McNeill, R. 1989. The Economic Theory of Water Pricing. Environment Canada, Inland Waters Directorate, Pacific and Yukon Region, Vancouver.

National Water Council 1980. Leakage Control, Policy and Practice. Standing Technical Committee Report No. 26, London.

Newton, T. 1989. Maximum Control of Otherwise Unaccountable Water Loss Factors, from Leakage to Waste. In: Interregional Seminar on Water Resources Management Techniques for Small Island Countries. UNDTCD Report No. ISWSI/SEM/38, United Nations Development Programme, New York.

Palantzis, C. 1989. Waste Prevention and Detection of Leakages. In: Proceedings of the Seminar on Water Management in Small Island States. Commonwealth Engineer's Council, Nicosia, Cyprus. pp. 60-63.

Perrens, S.J. 1982. Effect of Rationing on Reliability of Domestic Rainwater Systems. In: Proceedings of the International Conference on Rain Water Cistern Systems, Water Resources Center, University of Hawaii, Honolulu. pp. 308-316.

Postel, S. 1985. Conserving Water: The Untapped Alternative. Worldwatch Paper 67, Worldwatch Institute, Washington.

Postel, S. 1984. Water: Rethinking Management in an Age of Scarcity Worldwatch Paper 62, Worldwatch Institute, Washington. pp. 55-65

Rousseau, S.H. and A.P. Chandraratne 1986. Reduction of Unaccounted for Water in Seychelles. Water Supply, 4(2):75-82.

Sharp, I. 1989. Water Supply Leakage, Detection and Control Options. In: Interregional Seminar on Water Resources Management Techniques for Small Island Countries. UNDTCD Report No. ISWSI/SEM/38, United Nations Development Programme, New York.

Sims, J.H., D.D. Baumann, J.J. Boland, K. Alley, and B. Kranzer 1982. Consumer Adoption of Water Conservation. Southern Illinois University, Carbondale.

UNDESD [United Nations Department of Economic and Social Development] 1992. Water Resources Management Techniques for Small Islands. Report No. INT-88-R41, United Nations, New York.

UNESCO [United Nations Education, Scientific and Cultural Organization] 1991. Hydrology and Water Resources of Small Islands, a Practical Guide. Studies and Reports on Hydrology No. 49, UNESCO, Paris.

UNESCO [United Nations Education, Scientific and Cultural Organization] 1994. Efficient Water Use. UNESCO-ROSTLAC, Montevideo.

White, A. 1981. Community Participation in Water Supply and Sanitation: Concepts, Strategies and Methods. International Reference Centre for Community Water Supply and Sanitation Technical Paper No. 17, IRC, The Hague.

WHO [World Health Organization] 1989. Decade Progress and Problems in Pacific Island Countries. World Health Organisation Interregional Seminar on Water Resources Management Techniques for Small Island Countries Report No. ISWSI/SEM/23, WHO, Geneva. 9pp.

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