TABLE OF CONTENTS Nowadays, in countries with limited water resources and increasing private sector involvement in water supply, it is often both unacceptable and uneconomical to design a water-treatment plant to treat a greater quantity of water than will be required within a reasonable number of years. More than this, it is often economic to manage demand for water to a level that minimizes the investment in new water-resources and treatment plant. This chapter presents an introduction to water demand and losses from water systems. Demand is considered in very broad terms with the aim of identifying the major components and giving an indication of their magnitude, and how demand varies over a year. Unaccounted-for-water is discussed in broad terms and the issues relating to it are covered in outline.
Water demand and use is a subject that has become very complex over the past few years. This reflects its increasing importance and the amount of effort spent in studying it.
In the UK, until 1988 water-supply systems were generally publicly owned, domestic water supplies in the UK were unmetered, and it was widely accepted that increased incomes and improved standards of living automatically meant increased water use. Demand was unmanaged and increased at a steady rate. It was assumed that countries with low water usage would in the fullness of time reach North American levels of prosperity and water usage. Water-supply systems were designed with generous amounts of spare capacity.
Things are very different now. This has come about...
