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Newsletter and Technical Publications

<Sourcebook of Alternative Technologies for Freshwater Augumentation in Africa>

2.4 WATER CONSERVATION

2.4.1 Urban Water Conservation

Technical Description

The techniques included in this option take various forms and include the following water conservation measures which may be implemented by local authorities:

  1. The development of an appropriate tariff policy: Under this approach, tariffs are levied as steep progressive rates, which subsidize the very poor and may also offer special rates for the promotion of industry. However, cost recovery is essential in order to ensure a sustainable operation, and pricing levels should be such so as to guard against water wastage.

  2. The metering of individual stands and flats: The metering of individual properties puts the burden for water conservation on the consumer, which is the most effective means of ensuring urban water conservation.

  3. The institution of efficient meter reading and billing mechanisms: Well-maintained and working meters, read accurately and regularly, and followed-up by efficient billing procedures ensure that consumers do not abuse municipal water supplies. Monitoring of such systems for changes in rates of consumption and rates of return or payment of bills provides accurate data for planning purposes. Relating consumption paid for to the amount of water produced provides a check on unaccounted for water and can alert the water utility of leakages or breaks in the supply system.

  4. The use of water-saving fittings: By using water-efficient fittings such as low flush toilets, low-volume shower heads and taps, and flow limiters, consumers can achieve the same degree of benefit from a lesser volume of water.

Extent of Use

Water conservation approaches have met with varied responses in the African region:

  1. Development of appropriate tariff structures is generally a weak area in most countries in Africa. While some form of tariff structure exists in all of the countries of Africa, those that have attempted to set economic tariffs still fail to separate the water account from the rest of the municipal (general) expenditure account, which typically negates the benefit to the water utility of setting economic tariffs. (Such benefits, include the availability of finances to update or expand their production and distribution networks; by considering water revenues as general revenues, the water utilities are forced to compete for funds with all other municipal services.) For this reason, privatization of water services is being encouraged in a number of African countries.

  2. Although metering is encouraged in most countries of Africa, not all consumers are metered appropriately. Bulk supplies and stand posts are common in the rural areas, while, in large cities, only the affluent urban areas are typically metered.

  3. Billing mechanisms are in place in most countries of Africa, but these are not properly monitored. Lack of monitoring of payments significantly reduces the recovery rate for monies invested in water treatment and distribution. Unaccounted for water, including illegal connections, accounts for up to 30% of potable water generated in most countries. Likewise, lack of monitoring and efficient bill collection generally means that development of water distribution systems lags well behind the rate of urbanisation.

  4. Water saving fittings are being promoted in the dry countries of Africa, especially in Southern Africa.

Operation and Maintenance

The techniques described above are largely social strategies aimed at conserving water. Additional actions may be needed to operationalise these strategies. The following operation and maintenance techniques may be applied by water utilities when implementing water conservation measures:

  1. Pressure and flow control: Municipal water distribution systems normally have different ages. The tendency to leak is highest within the older portions of the network. To minimize leakages, it is essential that these different regions are zoned, and supply pressures be varied accordingly. Scheduled maintenance and leak detection systems are essential.

  2. Consumer information programming and conservation promotion: Conservation is promoted through the formulation of rules and regulations for promoting efficient use of water and minimizing wastage, and by effectively informing consumers of measures to reduce wastage of water.

  3. Distribution system maintenance: Corroding pipes cause leakage. Replacement of corroded pipes with non-perishable pipes, such as PVC piping, reduces water losses through leaks and ensures insofar as possible an uninterrupted supply to consumers. Regular maintenance reduces the risk of service interruptions due to breaks in the supply lines.

  4. Monitoring and policing in cases of misappropriation, theft and fraud: Replacement of faulty meters, training of meter readers, and efficient administrative oversight can detect and reduce illegal connections to distribution systems, thereby protecting the revenues of the water utility and reducing losses within the distribution system. For efficient operation and administration, it is essential that the network be divided into district meter zones and that an accurate and up-to-date map of the distribution system is made and maintained.

Level of Involvement

The urban authority is usually the major player in promoting water conservation. However, Government agencies as in some municipal areas may be the single largest consumer of water and should be enlisted to support the water conservation promotion program. Civic organisations and NGOs can also play a role in consumer information programming.

Costs

The costs vary depending on the measures taken, but more efficient use of water reduces or delays need for expenditure on new water supplies while ensuring that revenues are available for this purpose. Informational programming costs are minimal, especially if combined with other informational programming, such as school curricula in environmental sciences, health awareness campaigns or similar on-going activities, while provision of water-saving hardware to replace conventional plumbing supplies may be more costly. Manpower costs to improve distribution system maintenance and management are also relatively high but are typically offset by the increased revenue generated from these actions.

Effectiveness of the Technology

With effective leak detection and pipeline repair programmes in place, it has been categorically shown that the real savings far exceed the costs. For example, low volume flush toilet cisterns can reduce the volume per flush from 15 to 8 litres.

Suitability

Use of water conservation techniques is appropriate in all countries.

Advantages

Use of these techniques can result in saved water that can be put to other uses. There is a significant reduction in costs, and an increase in water utilization efficiency (and revenues). Capital projects for the construction of new water reservoirs may be deferred to a latter date, or capital made available for expanding the distribution system to meet new demands.

Disadvantages

Some expenditure is necessary to put a water conservation programme into action. Once the system is in place, use of water saving fittings may reduce wastewater flows to below the design flows for older trunk sewers and can sometimes result in blockages, necessitating a system redesign and retrofit. While the cost of such actions may be offset to a degree by increased revenues generated by charging consumers an economic rate for water, services charged at economic rates may be too expensive for the poorest segment of the community to afford, requiring additional arrangements to minimise illegal connections to the system.

Cultural Acceptability

No cultural problems have been noted, although the societal implications of charging economic rates for water should be recognised and accommodated in an equitable manner.

Further Development of the Technology

There is need to undertake studies to correlate soil resistivity with leak occurrence in, especially, steel water mains, taking into account pipe age and technical specifications. Research is also necessary to determine the most appropriate management systems required for water conservation in Africa. In cases where low volume fittings are adopted, it is necessary to consider their impact on trunk sewer slopes and reduced flows.

Information Sources

Contacts

Castle Brass Holdings (Pty) Ltd., Post Office Box 4082, Luipaaardsvlei 1743, South Africa.

City Engineer's Department, Post Office Box 4323, Johannesburg 2000, South Africa.

Bibliography

American Waterworks Association s.d. Water Conservation Management. Washington, DC.

City Engineer's Department 1989. Water Loss Analysis on Municipal Distribution Systems. Water Research Commission Report No. 157/1/89, Pretoria.

Holland, J.R. and S.M. Holland 1994. Urban Water Supplies Conservation Study for MLGRUD. Emergency drought recovery and mitigation programme.

National Building Research Institute 1986. Water Economy Measures. Guidelines for Local Authorities. Water Research Commission, Pretoria.

Jeffcoate, P. and A. Saravanapavan 1987. Working Guidelines for the Reduction and Control of Unaccounted For Water, World Bank Technical Paper No. 72, Water Supply Operations Management Series, Washington, DC.

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