1. SWITCH Training Kit: Pilot Training, Entebbe, 28-29 July 2010 Water Demand Management in the City of the Future Forecasting water demand – why is accurate demand forecasting important?

2. Why demand forecasting?  To develop a projection or ‘reference case’ of future water demand in a given region  To help understand the gap between supply and demand Time Water Surplus Deficit Gap

3. What factors affect demand for water?

4. Average Demand and Peak Demand  Demand management is mainly concerned with consumption of water resource per year oi.e. average demand  Short-term fluctuations in demand oTime of year / temperature (higher in hot periods) oDays of the week (variation in commercial / institutional / industrial / household / tourism uses) oTime of day Fluctuations in demand often managed using storage Peak demand determines system design, and management of peak demand may be valuable

5. Water Demand has many components!

6. Historical demand forecasting  Historical/current per person water demand (l/p-d) oHistorical growth in demand  Forecast water demand by multiplying the per person demand by projected population  It is a quick and easy method  Limitations oOnly projecting current/past situation which may have been affected by ‘other factors’ such as climate oDoes not account for changes in consumption  Changes in use – e.g. showers, flush toilets, washing m/cs  Changes in technology and efficiencies

7. Inaccuracies of historical demand forecasting, example from Sydney

8. Comparison of methods of demand forecasting

9. Demand chart

10. Sector - System Analysis

11. Sectors and customers

12. End-use analysis  Separate water demand into different sectors (e.g. residential, industrial)  Separate residential into end uses (e.g. showers, toilets) and estimate change over time  Benefits oDetailed understanding of ‘how’ water is used and how this may change over time oUses the concept of the ‘unit of service’ and not just ‘supplying a volume of water’  Limitations oData on end uses may not be available oFull analysis requires a major effort (but useful results and priorities may be obtained through limited study)

13. End use data from SWITCH Alexandria workshops

14. Data collection for demand forecasting The System – Service Provider Bulk water Metered water Other supplies The System – The customer Demographic data Stock data End-use data Surveys Other Govt Statistics Questionnaires Surveys Data loggers Diaries Other studies Surveys Other Govt Statistics Surveys

15. Example of End Use Consumption

16. Residential end-uses to consider / collect data for analysis  Indoor end uses oToilet oBath oShower oWash basin oLaundry tap oWashing machine oKitchen tap oDish washer  Outdoor end uses o Lawn/garden irrigatn o Livestock o Car washing o Pool etc o Evaporative AC  Home business use o Tea shop, Hair salon, Brewing etc

17. How much water is used?

18. Toilet water usage projections for Sydney, Australia

19. Single residential household demand (700 m3/hh/a) – Alice Springs, Australia

20. Forecasting using end use analysis

21. Acknowledgements  Sam Kayaga, WEDC UK  Stuart White and Andrea Turner, Institute for Sustainable Futures, University of Technology, Sydney, Australia