Outline. Introduction Importance of Water. Water Resources and Environmental Issues 12/1/2016

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1 Audit & Budgeting: Resources and Environmental Perspectives Prof T. I. Eldho Department of Civil Engineering IIT BOMBAY Outline Introduction Resources & Environmental Issues Resources - Indian Scenario Supply & Issues Auditing Necessity & Objectives Auditing Preparation & Planning Audit - Methodology Case Study Conclusions 1 Source: 2 Too much water Too little water Poor-quality water Introduction - Importance of water Introduction Importance of is one of our most important natural resources and Scarcity may be the most underestimated resource issue facing the world today. 3 4 Too much water Too little water Poor-quality water Resources and Environmental Issues 5 Developing Management schemes became necessary! 6 1

2 Resources Issues Impacts of climate change on water availability and weather patterns Influence of location (climate, geography and population) on water availability (rainfall, floods and drought) Impacts of water stress (both drought and flood) on health and wellbeing of societies Management Main Issue -The basic processes of managing water for human use are: collection storage treatment and, distribution of water. Environmental Issues Can arise in fields of Wastewater, storm water and water treatment Solid waste management Air pollution control Hazardous waste remediation Waste minimization and pollution prevention Risk assessment and safety engineering recycling and reuse conservation 7 8 Declining Availability Potentially significant demand supply gap 9 Source: Arnell N.W. Climate change and global water resources: SRES emissions and socioeconomic scenarios, Global Climate Change, 14(1), (2004) 10 Source: 2030 Resource Group Report titled Charting Our Futures, Over-exploitation of Groundwater Global withdrawal of water for agriculture, industry and municipal use, and total use, in liters and gallons per capita per day, Source: Gleeson, T.,Wada, Y., Bierkens, M. F. P. & van Beek, L. P. H. Nature 488, (2012) Agri: Mun: Industrial:: World: 70: 15: 15; India - 83: 9: 8. 2

3 Too much water Too little water Poor-quality water INDIA S LAND RESOURCE, IRRIGATION 13 India s Resources- Indian Scenarios AND FOOD PRODUCTION India has 2% of world s land, 4% of freshwater, 16% of population, and 10% of its cattle. Geographical area = 329 Mha of which 47% (142 Mha) is cultivated, 23% forested, 7% under non-agri. use, 23% waste. Per capita availability of land 50 years ago was 0.9 ha, could be only ha in Out of cultivated area, 37% is irrigated which produces 55% food; 63% is rain-fed producing 45% of 200 M t of food. In 50 years (ultimate), proportion could be 50:50 producing 75:25 of 500 M t of required food. Blue revolution for a Second Green Revolution Agricultural Production Command area irrigation Population 33 crores m.t 200 m.t 22.6m. 90 m. ha ha 100 crores 252 m.t ~120 m.ha 128 crores SKEWED DISTRIBUTION - WATER AVAILABILITY Inter-basin transfer of water : a key need SOME INFERENCES FROM RIVER BASIN STATISTICS Himalayan Rivers : 300 utilizable, 1200 BCM available. Himalayan large dams presently store 80 BCM. New dams under consideration could store 90 BCM. Peninsular Rivers : 400 utilizable, 700 BCM available. Peninsular large dams presently store 160 BCM. New dams under consideration could store 45 BCM. In all, large dams presently store 240 BCM. New dams under consideration could store 135 BCM. Total storage thus could be 375 BCM only. India s Present Yearly Balance, (Km 3 = BCM)- SUMMARY Precipitation = 4000 Present Withdrawal = 630 = 58% Inflow = 400 Still available = 470 = 42% Extendable = +300 = 28% Total = 4400 USES % ET = 2200 Irrigation = 83.0 Infiltration = 300 Drinking / Municipal = 4.5 Available = 1900 Industry = 3.0 Energy = 3.5 Utilizable / = 1100 Others = 6.0 Developable Extendable = +300 Total

4 WITHDRAWAL OF WATER- 2050, AVAILABILITY India s Yearly Requirement in 2050 (Km 3 = BCM) For growing food and feed at 420 to 500 million tonnes = 628 to 807 BCM Drinking water plus domestic and municipal use for rural population at 150 lpcd and for urban population at 220 lpcd = 90 to 110 BCM Hydropower and other energy generation = 63 to 70 BCM Industrial use = 81 to 103 BCM Navigational use = 15 BCM Loss of water by evaporation from reservoirs = 76 BCM Environment and ecology = 20 BCM Total 970 to 1200 BCM Availability 1100 to 1400 BCM supply costs (1998 dollars / 1000 cub m) for different technologies Technology ($/1000 m3) Source Large storage projects Keller Medium and small storage projects Keller Micro storage projects Keller Dug storage OAS, 1997 Groundwater development &pumping Keller Groundwater recharge Gleick, 1993 Conservation practices Keller et al., 1998 Recycling wastewater (secondary treatment) Gleick, 1993 Diversion projects (interbasin) Gleick, 1993 Reverse osmosis (for brackish water) Gleick, 1993 Recycling wastewater (advanced water treatment Gleick, 1993 Distillation Gleick, 1993 Desalinization of seawater Keller et al., Source: Paper by Andrew Keller and David Seckler (IWMI) on topic scarcity and the role of storage in development, 1999 Where does the water come from New dams - inter-basin transfer Groundwater - underdeveloped Demand Management savings - increase in efficiency, reduce evaporation. productivity - increases in crop per drop Trade (virtual water), import food. Indian Scenario 22 India sustains nearly 17 per cent of the world s population but is endowed with just four per cent of global water resources. About 50 per cent of annual precipitation is received in just about 15 days in a year Limited storage capacity of 36 per cent of utilizable resources Leakage and inefficiencies in the water supply system waste nearly 50 per cent of usable water The groundwater level is declining at the rate of 10 cm per year Over 70 per cent of surface water and ground water resources are contaminated All this is leading towards a water scarce situation in many parts of the country Source: Kumar S V, Bharat G K(2014), Perspectives on a Resource Policy for India, The Energy and Resources Institute, TERI, New Delhi. Urban water Issues in India Inconsistent supply (2-5 hours) with high leakages, thefts High Disparity in per capita water supply High Unaccounted water in Urban water supply (generally 20-50%) Very low coverage in metering quality issues tariff does not represent the actual O&M, social and environment cost of water Fall-outs in India Prioritization between domestic, agricultural and industrial water needs Zero sum game of water management", is one where authorities increase water supply to one user by taking it away from another Increasing industrial water usage causes increase in conflict between local communities and the industry, on issues ranging from water pollution to water scarcity Auditing can help in major way! 23 Source: Anshuman, Major Challenges in Urban water sector, Global/Indian Scenario, July Source: 4

5 Other Issues Weak legal and institutional framework Security Juridical Security Inefficient and unsustainable investments in infrastructure Scarce hydro-meteorological information for decision making Disaster prevention, control and protection Too much water Too little water Poor-quality water Supply & Issues Auditing part of Integrated and environmental management approaches 25 Source: 26 Need for Successful Management Practices Sector Issues & Challenges Losses many times UFW > 50% Equitable distribution (Alternate day / 2 hrs/day) Accountability to Slums (inefficient system) network coverage and inadequacy of network supply management during summer peak demand Old and inefficient assets Delay in capacity augmentation for future demand from limited water sources. Capital availability Low water tariff and Poor billing mechanism. Lack of professional approach 27 Source: 28 Issues & Challenges Eg. Nagpur City (before implementation of JnNURM) Successful Management Practices Require Audit 1. Integrated Approach 2. Address both Engineering + Behavioral Practices 3. Procuring Accurate baseline data 4. Logical sequence implementation in phases 5. Not only how much water but how it is used 6. Quality versus Application matching 7. Considering True Cost of 8. Understanding Life Cycle Cost Source: Dasgupta, P (2011), Audit in Industry CII s Perspective, National Seminar on Standards for Quality and Empowerment, New Delhi 5

6 Audit & Efficiency Too much water Too little water Poor-quality water Audit Necessity & Objectives Audits - Definition Unaccounted-For (UFW) Audit - Assessment of the capacity of total water produced by Supply Authority and the actual quantity of water distributed throughout the area of service of the Authority, thus leading to an estimation of the losses. It identify how much water is lost & its costs. Not all the water supplied reaches the customer! Not all of the water that reaches the end user is measured or paid for Also known as non-revenue water or Unaccounted-For (UFW) which is the difference between the quantity of water produced and the quantity of water which is billed or accounted for Audits - Objectives To assess the following: produced used Losses both physical and non-physical, Identify Unaccounted-For (UFW) To identify and prioritize areas which need immediate attention for control. Thus Audit is a Systematic Approach of Identifying, Measuring, Monitoring and Reducing the Consumption by various activities by a user Why Audits. A Comprehensive Audit gives a detailed profile of the distribution system and water users, thereby facilitating easier and effective management of the resources with improved reliability Why Audit It helps in correct diagnosis of the problems faced in order to suggest optimum solutions Effective tool for realistic understanding and assessment of the present performance level and efficiency of the service Shows adaptability of the present system for future expansion & rectification of faults during modernization

7 Why Audits In Irrigation, Domestic, Industrial sectors Legal Requirement (In many states) CREP (Corporate Responsibility for Environmental Protection) stress regions Availability / Quality Too much water Too little water Poor-quality water Auditing Preparation, Planning & Methodology Corporate image Business risk involved - Sustainability Payback options in places of high water tariff for industry Audits in allocation Pollution control Monitoring Financial management Flood and drought management Information management Legislation The Indian government set standards for water management and the quality and use of water Protection Act, 1974 Air (Prevention and Control of Pollution) Act, 1981 Environmental Protection Act, 1986 Public Liability Insurance Act, 1991 National Environment Tribunal Act, 1995 Verification and updating of Maps: Mapping and inventory of pipes and fittings in the water supply system: If the updated maps are available and bulk meters are in position network survey can be taken up as a first step. Otherwise maps have to be prepared and bulk meters fixed. Installation of Bulk meters: Being a major activity, Bulk meters required at the following locations: All major system supply points. All tube wells which supply the system directly. Major transfer mains which are expressly required for audit. 40 Audit Preparation & Planning Monitoring Production & Distribution System Audit Analysis Assessment of leakage rates through the features of water supply system includes: Raw water transmission system Reservoirs Treatment plant Clear-water transmission system Inter zonal transmission system Tube wells Monitoring of water flow from distribution point into the distribution system (Waste Metering Areas,WMA). Consumer sampling. Estimating metered use by consumers. Estimating losses in the appurtenances and distribution pipe line network including consumer service lines. Analysis: Audit will provide accurate area wise losses to prioritize the area into 3 categories viz. Areas that need immediate leak detection and repair. Areas that need levels of losses (UFW) to be closely monitored. Areas that appear to need no further work at the current time. After water audit of few cities it has been established that the components of UFW may generally be as follows: Leakage (physical losses): 75 to 80% Meter under-registration: 10 to 15% Illegal/unmetered connections: 3.5 to 6% Public use: 1.5 to 3.5%

8 Losses: Losses & Leak Control Physical losses (Technical losses): pipes, joints & fittings, reservoirs & overflows of reservoirs & sumps. Non-physical losses (Non-technical losses/commercial losses): Theft of water through illegal, already disconnected connections, under-billing either deliberately or through defective meters, water wasted by consumer through open or leaky taps, errors in estimating flat rate consumption, public stand posts and hydrants. 43 Losses & Leak Control Objective of Leakage Control: To reduce losses to an acceptable minimum To meet additional demands with water made available from reduced losses thereby saving in cost of additional production and distribution. To give consumer satisfaction. To augment revenue from the sale of water saved 44 Leakage Detection & Monitoring Preliminary data collection and planning. Pipe location and survey. Assessment of pressure and flows. Locating the leaks. Assessment of leakage. Following equipment used for conducting tests for leak assessment: Road measurer. Pipe locator. Valve locator. Listening sticks or sounding rods. Electronic sounding rods. Leak noise correlator. A street water tanker attached to a pump with ease to fabricate pipe assembly with valves to control pressure. Turbine water meters with pulse head, pressure point and data loggers. Leak Locator. 45 Leakage Management in Mumbai - Issues Detecting leaks on 6000 Km network with sounding is difficult task because: Listening leak sound through Rod is highly skilled job. Traffic / parked vehicles / underground Cables are hindrances in sounding method. Pressures are low due to high peak. Supply hours are short in some zones as less as 90 minutes. Covering 6000 Km network in cyclic manner even twice a year would require huge manpower. Random Leak detection is a futile exercise unless backed by Audit / Leak assessment. The recommended course of action is: Extended supply hours can increase the efficacy of Leak detection. Pressures will be better due to lower peak in longer supply hours. Initially the Tracer gas method instead of sound listening method would be more effective. The provision of bulk flow measurements would facilitate the zones required to be given priority (with high NRW) instead of random leak detection. The bulk flow measurements with District Metering Areas (DMAs) will be next step. DMAs will be periodically checked for NRW and investigated in details if NRW is off limits. 46 Audit Methodology IWA/AWWA Audit Method: Balance 47 Own Sources Imported Total Total System System Input Input (allow ( allow for for known known errors) errors ) Exported Supplied Authorized Authorized Consumption Consumption Losses Losses Billed Authorized Consumption Unbilled Authorized Consumption Apparent Losses Real Losses Revenue Non- Revenue Billed Exported Billed Metered Consumption Billed Unmetered Consumption Unbilled Metered Consumption Unbilled Unmetered Consumption Unauthorized Consumption Customer Metering Inaccuracies Systematic Data Handling Error Leakage on Mains Leakage on Service Lines Leakage & Overflows at Storage 8

9 Auditing Information Building floor plan Plumbing drawings Facility operating schedules Number of employees and visitors Maintenance and janitorial schedules Lists of water-using equipment Number of plumbing fixtures Outdoor water use applications, quantity, and schedule Prior water and energy surveys bills for past two years Anticipated water billing rates for next two years Records of actual water use for last two years Maps showing location of each water meter Recommended flow rates of waterusing equipment Key Validation Areas of the Audit Bring the people from different functional areas together to confirm the various process data that goes into the water audit Verify the Production Meter Data The water audit starts here and errors in this data carry throughout the entire audit Learn how the customer billing system works Billings systems have been designed for financial reasons, but we now use their consumption data for multiple purposes Recognize some key leakage factors Gather data on leakage repair response time Evaluate pressure levels in your system Know your policy on customer service line leakage Data Collection Setting Reliable Inhouse Data Collection Procedures When launching the auditing process, it is important to bring together the utility staff most familiar with: Production Metering Customer Metering Customer Billing Distribution System operations & leak detection Mapping/Geographical Information Systems Hydraulic Modeling (if available) Strive to have the knowledgeable people participating- the water audit is not an administrative task (Don t assign water audit data collection to the secretary) 51 Accurately Quantifying Supplied This is the most important quantity in the Audit! It is the largest number in the Audit Any error in this value carries throughout the entire Audit Several steps exist to reliably quantify the water supplied quantity 1. Source water, imported water and exported water should always be metered 52 a. Ideally, these meters should be the continuously recording type ideally linked to a Supervisory control and data acquisition (SCADA) System b. If meters are not linked to a SCADA System, then data should be collected as frequently as possible, at least weekly c. If meters are not continuously recording type, and are read infrequently, plan to upgrade the metering installation as soon as possible Accurately Quantifying Supplied Accurately Quantifying Supplied Volumetric Meter Test Testing Approach Comparative Meter Test 2. Meters should be regularly verified for accuracy a. Large meters can be compared with an inline insertion or strap-on meter measuring flow downstream of the primary meter i. Make certain that the temporary metering location is representative and accurate ii. Strive for minimum 24-hr period if using this method iii. Philadelphia Department conducts over 50 verifications each year in this manner 54 b. Smaller meters might be tested using field test apparatus as is conducted on large customer meters c. Document/store the inaccuracy values to serve as a basis for data adjustments d. Recognize that calibration of the related instrumentation (differential pressure transmitters) does not verify the flow measuring capability of the meter! Insertion pito rod measuring and recording flow 9

10 Accurately Quantifying Supplied Accurately Quantifying Supplied 3. Meters should be recalibrated, repaired or replaced regularly to maintain reliable performance a. New, current-technology meters should replace dated or defective meters b. Permanently installed insertion type meters can be a less costly means of establishing or renewing reliable metering c. Refer to AWWA M33 guidance manual Flowmeters in Supply for information on meter selection d. Many dated meters exist throughout the North American water industry 55 Magnetic Flow meter replacement on 48-inch untreated water line 2008 in Philadelphia 4. Regularly determine Master Meter Error Adjustment a. Data should be reviewed at least weekly, but ideally, each business day, for trends/anomalies 56 b. Balance flows to account for storage level changes and district water transfers c. Adjust for recorded inaccuracy levels of given meters d. Adjustments due to data error e. Adjustments due to data gaps f. Aggregate master meter error is: i. Added if source meter under-registration exists ii. Subtracted if source meter over-registration exists 16-inch turbine meter on wholesale account being verified via inline pito rod Data Collection Unbilled Authorized Consumption Unbilled Authorized Consumption components metered and/or unmetered consumption, e.g.: Street cleaning Mains flushing Fire fighting Generally small portion of the water supplied volume Don t spend lots of time on quantify this value if data is not available Instead, use the default value for Unbilled Unmetered Consumption Improve data validity over time Audit Problems Faced Proper network details in the shape of maps not available (not updated with proper indication of appurtenances). Not much attention paid by authorities to water audit of the water supply schemes. Except few major cities, separate audit units not available with the Authority, and where available, the water audit staff not motivated enough to carry out the work. authorities not equipped with necessary equipment. Proper budgetary provision not available for carrying out continuous and effective water audit. Lack of co-ordination between Audit unit and operational and maintenance staff. No emphasis given on Information Education and Communication (IEC) activities for conservation of water Benefits of Audit Reduced water losses Financial improvement Increased knowledge of distribution system More efficient use of existing supplies Safeguarding public health and property Improved public relation Reduced legal liability 59 AWWA WLCC Free Audit Software: Reporting Worksheet Back to Instructions Reporting Year: /2007-6/2008 Reporting Worksheet Click to access definition Copyright 2009, American Works Association. All Rights Reserved. WAS v4.0 Audit Report for: Philadelphia Department Please enter data in the white cells below. Where available, metered values should be used; if metered values are unavailable please estimate a value. Indicate your confidence in the accuracy of the input data by grading each component (1-10) using the drop-down list to the left of the input cell. Hover the mouse over the cell to obtain a description of the grades All volumes to be entered as: MILLION GALLONS (US) PER YEAR << Enter grading in column 'E' WATER SUPPLIED Volume from own sources: 7 94, Million gallons (US)/yr (MG/Yr) Master meter error adjustment: 10 2, over-registered MG/Yr imported: n/a MG/Yr exported: 10 7, MG/Yr WATER SUPPLIED: 84, MG/Yr. AUTHORIZED CONSUMPTION Click here: for help using option Billed metered: 7 57, MG/Yr buttons below Billed unmetered: n/a MG/Yr Unbilled metered: n/a MG/Yr Pcnt: Value: Unbilled unmetered: MG/Yr 1.25% AUTHORIZED CONSUMPTION: 58, MG/Yr Use buttons to select percentage of water supplied OR value WATER LOSSES ( Supplied - Authorized Consumption) 26, MG/Yr Apparent Losses Pcnt: Value: Unauthorized consumption: 8 2, MG/Yr 0.25% 2, Customer metering inaccuracies: MG/Yr Systematic data handling errors: 5 4, MG/Yr Choose this option to enter a percentage of Apparent Losses: 6, MG/Yr billed metered consumption. This is Real Losses NOT a default value Real Losses = Losses - Apparent Losses: 19, MG/Yr WATER LOSSES: 26, MG/Yr NON-REVENUE WATER NON-REVENUE WATER: 27, MG/Yr = Total Loss + Unbilled Metered + Unbilled Unmetered 10

11 SYSTEM DATA Length of mains: 9 3,137.0 miles Number of active AND inactive service connections: 7 547,932 Connection density: 175 conn./mile main Average length of customer service line: ft (pipe length between curbstop and customer meter or property boundary) Average operating pressure: psi COST DATA Total annual cost of operating water system: 10 $219,182,339 $/Year Customer retail unit cost (applied to Apparent Losses): 9 $4.97 $/1000 gallons (US) Variable production cost (applied to Real Losses): 9 $ $/Million gallons PERFORMANCE INDICATORS Financial Indicators Non-revenue water as percent by volume of Supplied: 32.4% Non-revenue water as percent by cost of operating system: 17.8% Annual cost of Apparent Losses: $34,546,470 Annual cost of Real Losses: $4,245,264 Operational Efficiency Indicators Apparent Losses per service connection per day: gallons/connection/day Real Losses per service connection per day*: gallons/connection/day Real Losses per length of main per day*: N/A Real Losses per service connection per day per psi pressure: 1.79 gallons/connection/day/psi Unavoidable Annual Real Losses (UARL): 2, million gallons/year Infrastructure Leakage Index (ILI) [Real Losses/UARL]: 9.04 * only the most applicable of these two indicators will be calculated WATER AUDIT DATA VALIDITY SCORE: *** YOUR SCORE IS: 82 out of 100 *** A weighted scale for the components of consumption and water loss is included in the calculation of the Audit Data Validity Score PRIORITY AREAS FOR ATTENTION: Based on the information provided, audit accuracy can be improved by addressing the following components: 1: Volume from own sources 2: Billed metered For more information, click here to see the Grading Matrix worksheet AWWA Free Audit Software Grading Matrix Guidance on Use of Audit Data Functional Focus Area Audit Data Collection Short-term loss control Long-term loss control Target-setting Benchmarking Loss Control Planning Guide Audit Data Validity Level / Score Level I (0-25) Level II (26-50) Level III (51-70) Level IV (71-90) Level V (91-100) Launch auditing and loss control team; address production metering deficiencies Analyze business process for customer metering and billing functions and water supply operations. Identify data gaps. Conduct loss assessment Research information on leak investigations on a sample detection programs. Begin portion of the system: customer flowcharting analysis of meter testing, leak survey, customer billing system unauthorized consumption, etc. Begin to assess long-term needs requiring large expenditure: customer meter replacement, water main replacement program, new customer billing system or Automatic Meter Reading (AMR) system. Establish/revise policies and procedures for data collection Establish ongoing mechanisms for customer meter accuracy testing, active leakage control and infrastructure monitoring Begin to assemble economic business case for long-term needs based upon improved data becoming available through the water audit process. Establish long-term apparent and real loss reduction goals (+10 year horizon) Refine data collection practices and establish as routine business process Refine, enhance or expand ongoing programs based upon economic justification Conduct detailed planning, budgeting and launch of comprehensive improvements for metering, billing or infrastructure management Establish mid-range (5 year horizon) apparent and real loss reduction goals Annual water audit is a reliable gauge of year-to-year water efficiency standing Stay abreast of improvements in metering, meter reading, billing, leakage management and infrastructure rehabilitation Continue incremental improvements in short-term and long-term loss control interventions Evaluate and refine loss control goals on a yearly basis Preliminary Comparisons - Identify Best Practices/ Best can begin to rely upon the Performance in class - the ILI is very Infrastructure Leakage Index Benchmarking - ILI is reliable as a real loss (ILI) for performance meaningful in comparing performance indicator for comparisons for real losses real loss standing best in class service (see below table) For validity scores of 50 or below, the shaded blocks should not be focus areas until better data validity is achieved. 3: Systematic data handling errors Audit Keys to Reliable Data Collection Steps to set procedures for reliable water audit data collection Set reliable inhouse procedures Watch for flagged data in the AWWA Free Audit Software Built-in checks in the software help alert the auditor to data issues audit components to watch: Production Metering Volume from Own Sources and Imported quantities Exported water quantity Unbilled authorized consumption Systematic Data Handling Error Length of Private Pipe Annual Cost of Operating the System Be objective in grading all components refer to the grading matrix criteria 64 Case Study Thermal Power Plant Source: Enhancing water-use efficiency of thermal power plants in India: need for mandatory water audits, Policy Brief, Ed: Batra, R.K., TERI, December 2012 GOAL: Identify, quantify, and verify water losses and costs and Identify water efficiency resource opportunities Balance of Thermal Power Plant Specific Consumption (SWC) Actual Overall SWC about 5 m 3 /MW Scope for optimizing (Achievable SWC) 3 m 3 /MW

12 use before Audit Potential use after Audit Potential saving Immediate saving potential of about 23% of total intake water Significant financial savings from water saving interventions of about INR 7-9 Crores Cost benefit of water recycling system was positive with a payback period of just 2.3 years Concluding Remarks Comprehensive study/ diagnosis of the system Auditing based on the Issue(s) to address Audit validation for most water utilities is coming in trend to improve its efficiency, sustainability and public image For Auditing, it is key to assemble employees from the pertinent groups to contribute accurate data and knowledge of all the operations Start in basic mode, and improve incrementally Auditing increase the efficiency of the water supply Dr. T. I. Eldho Institute Chair Professor, Department of Civil Engineering, Indian Institute of Technology Bombay, Mumbai, India, eldho@iitb.ac.in Phone: (022) ; Fax: