This project was intended to provide the most detailed and comprehensive picture possible of Melbourne’s recent residential water use. This included a stock survey of all major water-using appliances and the associated pattern of use through home visits and a questionnaire. It also included the measurement and logging of all water uses in a sample of homes, that also enabled the identification of appliances, flow rates, durations and times of use.
Melbourne’s three water retailers — City West Water, South East Water and Yarra Valley Water — have previously undertaken such separate studies for their specific residential customer bases and published individual reports. This approach unfortunately did not allow a ready comprehension of typical water use parameters across the entire Melbourne Region. For instance, while the median shower duration for each water retailer’s licence area may be known, the median for the Melbourne Region as a whole cannot be elucidated without a pooling and re-analysis of all water retailers’ data. This project was intended to remedy this situation, and provide further clarity on Melbourne-wide residential water usage.
These Melbourne-wide parameters of water use are often required in metro-wide planning, and they also allow a direct comparison of Melbourne’s water use characteristics with those of other cities in Australia and overseas. For instance, it is very common for comparative statistics to be prepared for all capital cities in Australia. As Melbourne is the only capital city with more than one water retailer, this proposed a unique situation that needed to be addressed.
Appliance stock surveys are undertaken once every four years by Melbourne’s water retailers. These involve visiting a representative sample of homes to determine the characteristics of water use appliances by inspection and measurement, and the way that they are used by interviewing the residents. Residential end use measurement involves the measurement and logging of all water use in a sample of homes at very short time intervals of as little as every 5 seconds, so that the use of each appliance generates a distinctive signature trace. This allows for the analysis of major characteristics of use.
Melbourne’s three water retailers have previously published individual reports of their residential appliance stock surveys and end use measurement studies. These were consolidated into metro-wide reports. The work required the pooling of data from the three water retailers, a check of data consistency, the correction of errors and re-analysis of the data to derive pooled statistical variables and frequency curves. The larger sample sizes enabled greater statistical validity and improve confidence levels. Because of the massive amount of data involved, software programs were written to expedite the process and to provide error-checking. The results were continuously reviewed by experts from the water retailers to ensure accuracy, realism and completeness.
The outcome of the project is a set of three related documents:
(1) Water Appliance Stock Survey and Usage Pattern, Melbourne 2012;
(2) Melbourne Residential Water End Uses, Winter2010/Summer 2012; and
(3) Melbourne Residential Water Use Studies which is a concise summary of the previous two documents.
All three documents were desktop-published to an attractive format and are available for download from the Knowledge Hub.
The reports provide a unified understanding of how Melbourne’s households use water for metro-wide planning purposes, and for comparison with other cities in Australia and overseas. These reports are the first such studies in Australia to be published for post-drought water use behaviours over a summer period. For the first time, they have enabled pie charts showing a breakdown of water use by appliance to be constructed for the entire Melbourne Region as a whole. They are expected to be widely requested by water utilities, research organisations, government departments, educational institutes and consultants in Australia and overseas.