Twort's Water Supply

Malcolm J. Brandt, K. Michael Johnson, Andrew J. Elphinston, Don D. Ratnayaka

• Publisher: Butterworth-Heinemann
• Year: 2016
• eBook ISBN: 9780081000434
• Edition: 7
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

Twort's Water Supply, Seventh Edition, has been expanded to provide the latest tools and techniques to meet engineering challenges over dwindling natural resources. Approximately 1.1 billion people in rural and peri-urban communities of developing countries do not have access to safe drinking water. The mortality from diarrhea-related diseases amounts to 2.2 million people each year from the consumption of unsafe water.This update reflects the latest WHO, European, UK, and US standards, including the European Water Framework Directive. The book also includes an expansion of waste and sludge disposal, including energy and sustainability, and new chapters on intakes, chemical storage, handling, and sampling. Written for both professionals and students, this book is essential reading for anyone working in water engineering.- Features expanded coverage of waste and sludge disposal to include energy use and sustainability- Includes a new chapter on intakes- Includes a new chapter on chemical storage and handling

Chapter 1

The Demand for Potable Water

Abstract

Understanding the supply and demand water balance is fundamental to managing a water utility business. This chapter discusses the components of demand; revenue water comprising domestic, industrial, commercial and institutional, public and miscellaneous use. Comparative tables of per capita consumption illustrate both household size and regional variations. Non-revenue water; real and apparent water losses are categorized. Leakage, being the significant component of water losses, is discussed in both absolute terms and with reference to the International Water Association Infrastructure Leakage Index and alternative performance metrics. Sections address variations in demand, consumption surveys, appliance usage, revenue metering, price elasticity of demand, growth trends and assessing demand in developing countries, including standpipe usage.

Keywords

Consumption; consumer metering; demand forecasting; demand management; domestic demand; Infrastructure Leakage Index; leakage reduction; losses; non-domestic demand; non-revenue water; price elasticity; standpipes; water appliance usage; water balance; water conservation

1.1 Categories of Consumption

The demand for potable water is made up of authorized consumption by domestic and non-domestic consumers and water losses. Domestic consumers use water within the household; for drinking, personal hygiene, cooking and cleaning, and outside the dwelling: for cleaning patios, irrigating gardens, filling ponds and swimming pools, and washing cars. Non-domestic consumption comprises industrial, commercial, institutional and agricultural demand legitimately drawn from potable water mains. This category also includes legitimate public use for irrigating public parks and green areas, street cleaning, flushing water mains and sewers and for firefighting.

Water is delivered to premises via service connections, the size of which depends on the demand from the premises. The majority of service connections feed single premises, but some supply a group of adjacent premises or a private development, such as an industrial estate, commercial complex or group of dwellings accessed from a private road.

Commercial and industrial supplies are generally fitted with an operational revenue meter because they represent a major source of income to a water utility. Small shops and offices occupied only in the daytime are also generally metered even though their consumption is small. In many countries where the national government, state or city owns the utility, large quantities of potable water used for watering public parks and green areas and within government offices, military establishments and other institutional buildings are often not metered nor accounted for as revenue.

Domestic revenue meters are widespread although not universal. For example in the USA, mainland Europe and Australia meter penetration is effectively 100%; in England and Wales in 2012 nearly 40% of domestic supplies were metered with individual meter penetration ranging between 10% and 75% for the 22 water companies; while in Scotland and Northern Ireland domestic consumers are not currently metered. However, the underlying issue related to the effectiveness of domestic metering is one of operability not its coverage.

The world population is estimated to be in excess of 7 billion and international organizations estimate that over 1.4 billion people live in extreme poverty; nearly 900 million people live in slum dwellings and over 700 million do not have access to an improved drinking water supply (WB, 2013; WHO, 2014; UNESCAP, 2013). Accordingly, not all consumers are supplied through a domestic service connection. In many cities, more typically in Asia and Africa, supplies are not 24-hour, do not reach 100% of the urban population or the pressure is so low that many consumers receive an intermittent supply. The Asian Development Bank (ADB) survey of 2005 (ADB, 2007a) showed that nine of 40 Asian water utilities surveyed did not have a 24-hour supply and that only eight of the utilities supplied 100% of the population in their service area, a connection being either in-house or a communal yard tap or standpipe.

A survey by the ADB published in 1997 (ADB, 1997) reported that of 27 cities in Asia with populations ove...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Authors’ Biographic Details
• Foreword
• Preface
• Abbreviations for Organizations
• Contributing Authors, Reviewers and Advisors
• Chapter 1. The Demand for Potable Water
• Chapter 2. Water Supply Regulation, Protection, Organization and Financing
• Chapter 3. Hydrology and Surface Supplies
• Chapter 4. Groundwater Supplies
• Chapter 5. Dams and Reservoirs
• Chapter 6. Intakes
• Chapter 7. Chemistry, Microbiology and Biology of Water
• Chapter 8. Storage, Clarification and Chemical Treatment
• Chapter 9. Water Filtration
• Chapter 10. Specialized and Advanced Water Treatment Processes
• Chapter 11. Disinfection of Water
• Chapter 12. Chemical Storage, Dosing and Control
• Chapter 13. Energy Use, Sustainability and Waste Treatment
• Chapter 14. Hydraulics
• Chapter 15. System Design and Analysis
• Chapter 16. Distribution Practice
• Chapter 17. Pipeline Design and Construction
• Chapter 18. Valves and Meters
• Chapter 19. Pumping, Electrical Plant, Control and Instrumentation
• Chapter 20. Treated Water Storage
• Conversion Factors
• Index
• List of Captions for Plates