Dealing with the Complex Interrelation of Intermittent Supply and Water Losses

Bambos Charalambous, Chrysi Laspidou

• Publisher: IWA Publishing
• Year: 2017
• eBook ISBN: 9781780408880
• Topic: Biological Sciences
• Subtopic: Applied Sciences
• Index: Biological Sciences

The book provides a scientific approach into appraising Intermittent Water Supply (IWS) on a global scale through the analysis of available information and data based on a structured methodology for estimating the population affected by IWS worldwide both by country and by geographical regions. The root causes and the implications of IWS are dealt with in a concise manner providing a detailed account of the reasons for resistance to change towards 24x7 supply. A major contribution of the book is in providing an understanding of water losses in the context of IWS as well as the related difficulties in leakage detection and metering under such conditions. A methodology is presented for transitioning from IWS to continuous supply covering technical, social and communication issues which are considered of paramount importance for a successful transition. Relevant case studies from across the globe are included in the book to provide evidence based information and data relating to the many and diverse challenges faced daily by water utilities operating their networks under IWS.

© IWA Publishing 2017. Dealing with the Complex Interrelation of Intermittent Supply and Water Losses

Bambos Charalambous and Chrysi Laspidou

doi: 10.2166/9781780407074_001

Chapter 1

Introduction

Chrysi Laspidou, Alexandra Spyropoulou and Bambos Charalambous

Intermittent Water Supply (IWS) may be defined as piped water supply service that delivers water to users for less than 24 hours in one day. In an intermittent supply situation the consumers secure their water through the use of ground and/or roof tanks, where water is stored during the provided supply time. In a number of instances it could be that IWS is temporarily established to deal with extremely low water reserves due to prolonged drought or low rainfall periods resulting in temporary depletion of available water. In other instances IWS is a normal method of operation, such as in many countries in Asia, Africa and Latin America mainly due to the high levels of leakage in the networks, which cannot sustain continuous supply.

There is a lot of misconception surrounding IWS, the purpose it serves and the pressures it alleviates. Before getting into all the details and listing several arguments against IWS and presenting a useful guide for water specialists on how to deal with the critical issues leading to intermittent supply and how to transition to a 24 × 7 regime, a succinct list of reasons why IWS should be avoided is presented here. The list may shed light on issues that are often not readily acknowledged by many water professionals around the world; more data to support each reason presented here are included throughout the Chapters of this book.

1.1 10 REASONS WHY IWS SHOULD BE AVOIDED

(1)May seem to be a water saving measure however in the long run greater quantities of water will be lost through increased leakage and wastage compared to the quantities that may initially be saved.

(2)Has a detrimental effect on the structural integrity of the distribution network thus leading to quicker asset deterioration.

(3)Results in a substantial increase in the number of pipe bursts in mains and service connections thus increased leakage.

(4)Creates water quality problems, which are detrimental to human health and wellbeing and cause serious illness.

(5)Has an adverse financial effect on the water utility resulting in lower water sales and higher costs due to additional O&M activities needed to run IWS.

(6)Results in customer dissatisfaction and reluctance to pay due to poor quality of service provided.

(7)Entails an additional financial burden on the consumers.

(8)Is not an effective Water Demand Management measure.

(9)Is not considered an appropriate intervention to drought/water shortage.

(10)Takes “1 hour” to introduce but years to reverse.

1.2 DEFINITION: THE COMPLEXITY OF DEFINING AND MEASURING IWS

Intermittent Water Supply (IWS) refers to piped water supply service that is available to consumers less than 24 hours per day. In many regions around the world and mostly in Low And Middle Income (LAMI) Countries, IWS systems are prevalent; the situation is usually credited to shortage in water supply. An attempt to find a formal definition of IWS from the literature sheds light to the ambiguity that surrounds the issue and the lack of standardization in the terminology, which by itself leads to more confusion and makes taking action to address the problems that surround IWS more difficult. According to Galaitsi et al. (2016), terms referring to intermittent water supply include irregular, unreliable, inadequate and poor supply as well as outages and scarcity.” Intermittency can be daily, seasonal or occasional and be related to inter-annual variability in water. In an IWS situation, consumers usually secure their water supply through the use of ground and/or roof tanks or smaller containers, where water is stored during the length of time that the supply is provided. Thus, it is possible that even though a city operates under an IWS regime, some consumers–especially wealthy – may not actually experience IWS, due to the fact that they have invested in pumps, tanks, filters, etc., so they store water when it is actually running and have enough supplies of purified water to use throughout the day. It is worth noting that IWS is enforced not only in cases where there is water shortage but also where the hydraulic capacity of distribution networks is such that cannot satisfy demand as well as in cases where the network is severely deteriorated resulting in high leakage (Charalambous, 2015).

Though basic issues related to water scarcity and intermittent supply are not part of popular consciousness in High Income (HI) countries, their effect is truly global as this issue affects over a billion people worldwide. Intermittent water supply systems are found mainly in LAMI countries, including most of the countries of South Asia and Latin America (Vairavamoorthy et al. 2008). In Latin America and the Caribbean, it is estimated that 60% of the population is served by household connections having intermittent service (PAHO and WHO, 2001). In Africa and Asia, it is estimated that more than one-third and one-half of urban water supplies, respectively, operate intermittently (WHO and UNICEF, 2000). According to WSP (2010), no city in India has continuous water supply and even in major cities of India, water supply is as low as 1 hour per day or less and 2–3 hours of supply is considered acceptable. Currently, some 30 LAMI countries worldwide are considered to be water stressed. It is predicted that by 2050, the number of water-scarce countries will likely approach 35 (Vairavamoorthy et al. 2007).

Intermittent distribution is widely adopted in both LAMI (McIntosh, 2003; McIntosh & Yñiguez, 1997; Hardoy et al. 2001) and HI countries (Cubillo, 2004, 2005) and it is usually done in order to distribute limited water quantities to as many people as possible. In this area, the lack of natural resources management and network maintenance plans, explicitly considering the possibility of scarcity scenarios, produces unexpected water shortage situations that can be handled only by mean of emergency interventions (Fontanazza et al. 2007).

‘Full-pressure, “24 × 7” water supply remains a pipe dream in many cities’ (World Bank, 2004). With the water demand increasing, especially in LAMI counties, often water utilities felt they have little option but to supply water intermittently. In many LAMI countries, intermittent water supply is still considered the norm (McIntosh, 2003).

1.3 WATER USE UNDER IWS AND 24 × 7 REGIME

When comparing water uses under the two different regimes, IWS and 24 × 7, the following question arises: to what extent do intermittent supplies reduce the overall demand for water? Consumers hoarding large amount of water and discarding it during the next flush simply results in excessive consumption, which contradicts the general belief that intermittent supply reduces overall water consumption. There are cases that document that water consumption under an IWS regime can be as much as double compared to the consumption when 24 × 7 conditions IWS (Kumpe...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Contents
• List of Figures
• List of Tables
• List of Abbreviations
• Principal Authors
• Contributing Authors
• Acknowledgements
• Preface
• Chapter 1: Introduction
• Chapter 2: Global dimensions of IWS – number of people affected worldwide
• Chapter 3: Root causes and implications of IWS
• Chapter 4: Reasons for resistance to change towards 24 × 7
• Chapter 5: Understanding water losses in the context of IWS
• Chapter 6: Transitioning from IWS to continuous 24 × 7
• Chapter 7: Leakage detection under IWS
• Chapter 8: Metering under IWS
• Chapter 9: Communication with stakeholders
• Chapter 10: Case studies
• Index