Guideline for a robust assessment of the potential savings from water conservation and water demand management
Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Water loss in water distribution systems has been studied for many years in many countries and is continuously leading to the development of new concepts and theories, publications, guidelines and software models. Despite these developments, 45 % of water utilities in South Africa still do not understand the extent of water losses in the distribution systems that they operate (Wegelin et al., 2012:27). It is important, in terms of water services planning, that a realistic estimate of the potential savings from individual water conservation and water demand management (WC/WDM) measures is made as it impacts directly on water security and business matters. If the potential savings were incorrectly or inaccurately calculated, additional resources might have to be developed at short notice to be able to supply in the demand. Advanced software models, such as BENCHLEAK, PRESMAC, SANFLOW, AQUALITE and ECONOLEAK (McKenzie & Bhagwan, 2000) have been developed to quantify the extent of physical and commercial losses in water supply systems. Similar advanced models are available for estimating water demand. Such advanced models require numerous input parameters, each of which needs to be described accurately. The predicament is that such complex models are often simply not applicable in certain areas with limited resources and limited input data. In contrast, robust guidelines that are relatively insensitive to input parameters are useful in developing countries, where all input values for complex water demand models may be unavailable or inaccurate. No robust method has yet been developed for estimating the potential water savings that would result from WC/WDM interventions. A need thus exists to estimate water savings in a robust way with relatively few inputs. This guideline promotes the development of a robust WC/WDM strategy, based on a systematic and pragmatic approach, which requires less initial funding and develops with time. The methodologies developed by the Water Loss Task Force (WLTF) of the International Water Association (IWA), were used to develop six basic steps, which need to be followed to develop a WC/WDM strategy. During the six steps, the minimum requirements for implementing WC/WDM will be defined, the current water losses and efficiencies will be determined, and potential targets will be set based on national and international benchmarks. Once targets have been set, 20 key interventions were identified to address water use efficiency, and commercial and physical losses. The motivation behind each intervention is provided based on best practice, case studies and legal requirements. The model ensures that the potential savings from the various interventions are sufficient to ensure that targets are achieved, and if not, that targets must be revised. The potential savings from interventions are based on literature reviews and new formulas developed as part of this guideline. The results from the various interventions would enable the water utility to prioritise interventions. The guideline concludes with a flow diagram describing the methodology.