IWRM requires that the needs of all water users be balanced and that water resources not be compromised for the future by over-extraction. Efficient use of water is thus an important strategy in IWRM implementation/practice. The recognition of the limits to water supplies around the world has been growing, prompting a major shift in the approach to water management. The shift has gone from a focus on technical engineering for increasing supply, to instead managing demand.
Demand Efficiency (C6.01) includes many strategies towards that end, from technical interventions that increase the efficiency of appliances and industrial processes, to water conservation, and changing consumer behaviour either through the use of economic instruments or by public education. Demand management looks at changing demand and at the way people use water in order to achieve more efficient and cost effective water use. It aims directly to change human practice and behaviour. Consequently, it is linked closely to water regulations (A2), Economic Instruments (C7), and Tools on Promoting Social Change (C8). The push for water efficiency should be supported in the overall policy framework (A1) and be built into Planning for IWRM (C4).
Supply management (C6.02) itself involves the construction of physical infrastructure to capture or distribute more water for direct use. Recycling water (C6.03) or reusing it for multiple purposes is an important strategy for addressing water scarcity. It is where demand and supply management come together.
Efficiency in water management can be applied across sectors and to all levels: river basin level, community level, at the level of large users of water (utilities, industry), the agriculture industry, and the household level. For situations and levels of management that involve many different small uses and water appliances (such as residential water use), demand management can be extremely effective at reducing overall water consumption. At the industrial level large amounts of water can be conserved by changing the way water is used (e.g. decreasing pressure) or by reusing water multiple times for different functions that require successively lower quality water. In many developing regions, water supply is insufficient or irregular and therefore a combination of supply management and demand management will likely be required to achieve water security through IWRM.