Calculating Water Loss in the Distribution System

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What are the best methods to calculate/estimate the water loss in the water distribution network?

How can I calculate the Linear Water Losses Index (LWLI)? I need the formula for a community water distribution system of 10000 households. 

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10 Answers

  1. John

    I am not entirely sure about your definition of LWLI.  IWA uses Infrastructure Leakage Index (IFI) and in France the Linear Leakage Index (LLI) is in use.  Eddy Renaud's paper at https://hal.archives-ouvertes.fr/hal-00593479/document provides a comprehensive and detailed presentation of these and other indices including their formulae and worked examples.

    I would also support earlier references to the IWA Manual of Best Practice; Performance Indicators for Water Supply Services (3rd edition) http://www.iwapublishing.com/books/9781843390510/performance-indicators-water-supply-services-second-edition.   In addition I recommend "Losses in Water Distribution Systems - A Practitioners Guide to Assessment, Monitoring and Control" by Malcolm Farley and Stuart Trow (http://www.iwapublishing.com/books/9781900222112/losses-water-distribution-networks) and all Allan Lambert's work.

    As a general introduction on water losses "Sustainable Water" published by ICE is a good reference (http://www.icebookshop.com/bookshop_main.asp?ISBN=9780727757739).

    Good luck with your project.

     

     

     

  3. I am not sure whether any such universal formula for estimating water loss exist. Best way may be to use the factor or some assumed value or percentage which already exists for established water supply lines around the proposed project. In case no data available around then can use values assumed or observed in other countries for similar scheme as you are proposing. Hope this helps

  4. Dear John.

    Losses in water utility operations occur in two distinctly different manners.   Apparent losses  occur due to customer meter inaccuracies, billing system data errors and unauthorized consumption.  These losses cost utilities revenue and distort data on customer consumption patterns.  Losses also occur as  Real losses  or water that escapes the water distribution system, including leakage and storage overflows.  These losses inflate the water utility’s production costs and stress water resources since they represent water that is extracted and treated, yet never reaches beneficial use.

    Real Losses, Apparent losses, Non‐Revenue Water

    Different methods are available for detecting leakage such as ultrasound method.

     

    What is Unaccounted-For-Water?

    Definition

     Unaccounted-for water (UFW) represents the difference between "net production" (the volume of water delivered into a network) and "consumption" (the volume of water that can be accounted for by legitimate consumption, whether metered or not). UFW = “net production” – “legitimate consumption”

    Non-Revenue Water

    Non-revenue water (NRW) represents the difference between the volume of water delivered into a network and billed authorized consumption.

    NRW = “Net production” – “Revenue water”

    = UFW + water which is accounted for, but no revenue is collected (unbilled authorized consumption).

    Calculating Water Loss

    Water loss is expressed as

    • A percentage of net water production (delivered to the distribution system)

    • As m3/day/km of water distribution pipe system network (specific water loss)

    Others

    m3/day/connection

    m3/day/connection/ pressure

    Water loss as % of net water production is the most common.

    It could be misleading for systems with different net productions with same amount of real & apparent losses.

    Four Components of a Comprehensive Water Loss Control Program

    When considering a comprehensive water loss control program, four components are necessary:

    1. Leak Surveys and Leak Detection
    2. Speed and Quality of Repairs
    3. Pipeline and Asset Management
    4. Pressure Management

     

     

     

  5. International Water Association has defined an Infrastructure Leakage Index method which might be usefully referred here

  6. Using 1950's technology will certainly result in water loss. Too much time taken to measure the loss instead of either replacing old pipes or changing to current recycle technology. in a few words as possible.>collect rain water, use, store, build cistern,= to 2 years your water needs, biodigesters, biogenerators, save use pathogen and toxin free biomass for home garden, use solar, wind, bio energy with storage batteries  apx 2 years back up, Eliminate infrastructure, maintenance, taxes, reduced food needs, (green house for year round.

    The question is similar to measuring how many stars in our own galaxy.  Impossible to do. If done no relevance.  Added advantage, no chlorine ever needed, no more dumping into rivers, lakes, ocean.  In case you were wondering.   

  7. Calculation of water loss would be base on what is coming into the plant minus the consumption rate,bearing in mind the 10% unaccounted for water  which allow into the design of all treatment plant,correct me if I am wrong

  8. For me the best method is the water balance by IWA

  10. Dear John.

    Depending on your project task, and final result requirements there are different ways of calculating and evaluating water losses. Working with water losses last 10 years I can recommend you to start calculating water losses based on IWA blue pages where you can find some basic guidelines in water losses analysis. There are many good papers online for this subject on which you can refer to but try to stay in IWA methodology domain for first calculations.

    Basically your work will consist in several steps:

    1. GIS of water network

    2. Hydraulic model

    3. DMA zoning

    4. Field measurements

    5. Hydraulic model calibration for preforming further analysis and determine average pressure per DMA 

    6. Calculation of performance indicators (CARL, UARL, ILI, RL/m, RL/mH2O, RL/HC, etc.)

    Those indicators will give you starting point in decision making and defining further actions. You can avoid calibrated hydraulic model but then you need some other method of defining average pressure per DMA.

    If you have some other questions, feel free to contact me.

    Best regards...