dvgw-w 392 the german water loss guidelines · operating with system leakage above this level would...

Conferenze sulle Strategie di Gestione delle Perdite Idriche

1IWA Water Loss Task Force Visit ItalyGenova – Ferrara 15-19 May 2006

DVGW-W 392The German Water Loss Guidelines

Overview of the W 392 – and a comparison with the previous German regulations

Roland LiembergerRoland LiembergerLiemberger & Partners GmbHLiemberger & Partners GmbH


W392 The German Water Loss Guidelines

Background

Advanced leakage management was never an Advanced leakage management was never an issue in Germanyissue in GermanyThe old DVGW guidelines (valid until 2003) The old DVGW guidelines (valid until 2003) were from the early 80swere from the early 80sW392 is revolutionary for Germany and did only W392 is revolutionary for Germany and did only happen because of the close cohappen because of the close co--operation within operation within the IWA WLTFthe IWA WLTF



W392 and its predecessors

W 392 W 392 -- Network inspection and water losses Network inspection and water losses --activities, procedures and assessments replaces activities, procedures and assessments replaces three old guidelines, namely three old guidelines, namely

W 390 W 390 -- Control of Water Supply Networks Control of Water Supply Networks W 391 W 391 -- Water Losses in Water Distribution Systems Water Losses in Water Distribution Systems W 393 W 393 -- Leak Detection Methods for Water Leak Detection Methods for Water PipelinesPipelines



Structure of the W 392

1.1. ApplicabilityApplicability2.2. Standards and legal frameworkStandards and legal framework3.3. PrinciplesPrinciples4.4. Inspection of water supply systemsInspection of water supply systems5.5. Water losses in water supply networksWater losses in water supply networks6.6. Methods and measures for monitoring and reduction of Methods and measures for monitoring and reduction of

real lossesreal losses7.7. AppendicesAppendices



Chapter 4: Inspection

A comprehensive table of periodic inspections and A comprehensive table of periodic inspections and maintenance measuresmaintenance measuresLeakage Inspection frequency table:Leakage Inspection frequency table:

Maximum every 6 yearsMaximum every 6 yearsLowLow

Every 3 yearsEvery 3 yearsMediumMedium

AnnuallyAnnuallyHighHigh

Recommended Leak Recommended Leak Survey FrequencySurvey Frequency

Level of Real Level of Real LossesLosses



Chapter 5: Water Losses

"A precondition for any discussion of water losses "A precondition for any discussion of water losses are exact definitions of the components of the water are exact definitions of the components of the water balance."balance."



Water Balance (German)



Chapter 5: Water Losses

"A precondition for any discussion of water losses "A precondition for any discussion of water losses are exact definitions of the components of the water are exact definitions of the components of the water balance."balance."IWA standard water balance and definitions includedIWA standard water balance and definitions includedmajor improvement to W 391 major improvement to W 391 –– stated only that a water stated only that a water balance has to be establishedbalance has to be establishedInteresting is how the understanding of the reasons for Interesting is how the understanding of the reasons for real losses has changed: real losses has changed:



W 392 / W 391 Comparison (1)

Higher operating Higher operating pressures do normally pressures do normally NOT lead to higher NOT lead to higher levels of leakage (!)levels of leakage (!)

Changes in pressure Changes in pressure result in changes in result in changes in leakage in a nearly linear leakage in a nearly linear relationship. relationship.

Not mentionedNot mentionedVolume of water lost Volume of water lost from a leak depends on from a leak depends on flow rate and runtimeflow rate and runtime

(Old) W 391(Old) W 391W 392W 392




Type (texture) of soil is the Type (texture) of soil is the MOST IMPORTANT MOST IMPORTANT influencing factor.influencing factor.

Levels of unavoidable real losses Levels of unavoidable real losses (m3/h per km mains), depending (m3/h per km mains), depending on soil type, were listed in a table on soil type, were listed in a table and a diagram (to be used for and a diagram (to be used for mixed soil conditions).mixed soil conditions).

Soil: 3 parameters are Soil: 3 parameters are relevant:relevant:

AggressivenessAggressiveness

type (texture) of soiltype (texture) of soil

visibility of leaksvisibility of leaks

leaks often don't leaks often don't surface in gravel and surface in gravel and permeable rockpermeable rock

(Old) W 391(Old) W 391W 392W 392



The Famous W 391 Soil/Leakage Chart




Influencing factors with only LIMITED Influencing factors with only LIMITED RELEVANCE:RELEVANCE:

pressurepressureaverage diameteraverage diameterpipe materials and types of jointspipe materials and types of jointsdensity of fittingsdensity of fittingspipe depthpipe depthtype of beddingtype of bedding

Has been Has been removedremoved

(Old) W 391(Old) W 391W 392W 392



Like W 391, W 392 discourages the use of percentages

... is unsuitable as a technical performance indicator... is unsuitable as a technical performance indicator

... will always favour systems with high system input... will always favour systems with high system input

... recommended: m3/km/h... recommended: m3/km/hmentions: ... mentions: ... internationally often used unit m3/per internationally often used unit m3/per service connection per dayservice connection per day



Real Loss Targets in W 392

> 0.10> 0.10> 0.15> 0.15> 0.20> 0.20HighHigh

0.05 0.05 –– 0.100.100.07 0.07 –– 0.150.150.10 0.10 –– 0.200.20MediumMedium

< 0.05< 0.05< 0.07< 0.07< 0.10< 0.10LowLow

Type 3Type 3

RuralRural

Type 2Type 2

UrbanUrban

Type 1Type 1

Urban Urban --

large citieslarge cities

Network StructureNetwork StructureLevel ofLevel of

Real LossesReal Losses

[m3/km/h][m3/km/h]



Target Analysis

Background information from:Background information from:German National Report (Weimer D. 2001), BerlinGerman National Report (Weimer D. 2001), BerlinAverage operating pressure in Germany Average operating pressure in Germany assumed to be 30massumed to be 30mConnection density that formed the basis for the Connection density that formed the basis for the W 392:W 392:

Type 1: > Type 1: > 40 [connections per km mains] 40 [connections per km mains] Type 2: Type 2: 25 25 -- 40 per km 40 per km Type 3: < Type 3: < 25 per km25 per km



Targets interpreted by using l/conn./d

252537.537.55050Connection density Connection density used for calculationused for calculation

> 96> 96> 96> 96> 96> 96HighHigh48 48 -- 969645 45 -- 969648 48 -- 9696MediumMedium< 48< 48< 45< 45< 48< 48LowLow

Type 3Type 3RuralRural

Type 2Type 2UrbanUrban

Type 1Type 1Urban Urban -- large citieslarge cities



[[l/conn./dl/conn./d]]



Targets interpreted by using the ILI

> 2.0> 2.0> 2.5> 2.5> 2.8> 2.8HighHigh1.0 1.0 –– 2.02.01.2 1.2 –– 2.52.51.4 1.4 –– 2.82.8MediumMedium

< 1.0< 1.0< 1.2< 1.2< 1.4< 1.4LowLow

Type 3Type 3

RuralRural

Type 2Type 2

UrbanUrban

Type 1Type 1

Urban Urban --

large citieslarge cities



[m3/km/h][m3/km/h]



Australian Recommendations

PoorPoor3.0 3.0 –– 3.53.5

UnacceptableUnacceptable3.5 3.5 –– 4.04.0

FairFair2.5 2.5 –– 3.03.0ReasonableReasonable2.0 2.0 –– 2.52.5

GoodGood1.5 1.5 –– 2.02.0ExcellentExcellent1.0 1.0 –– 1.51.5

DescriptionDescriptionILIILI



AWWA - General ILI Targets

Source: AWWA Water Loss Control Committee Report, published in the AWWA Journal in August 2003 (Table 7, Page 76)

While operational and financial considerations may allow a long-term ILI greater than 8, such a level of leakage is not an effective utilization of water as a resource. Setting a target level greater than 8 – other than as an incremental goal to a smaller long-term target – is discouraged.

Greater than 8

Cost to purchase of obtain/treat water is low, as are rates charged to customers

Superior reliability capacity and integrity of the water supply infrastructure make it relatively immune to supply shortages

Water resources are plentiful, reliable and easily extracted

5 - 8

Water resources can be developed or purchased at reasonable expense; Periodic water rate increases can be feasibly effected and are tolerated by the customer population

Existing water supply infrastructure capability is sufficient to meet long-term demand as long as reasonable leakage management controls are in place

Water resources are believed to be sufficient to meet long-term needs, but demand management interventions (leakage management, water conservation) are included in the long-term planning

3 - 5

Water resources are costly to develop or purchaseAbility to increase revenues via water rates is greatly limited due to regulation or low ratepayer affordability

Operating with system leakage above this level would require expansion of existing infrastructure and/or additional water resources to meet the demand

Available resources are greatly limited and are very difficult and/or environmentally unsound to develop1 - 3

Financial ConsiderationsOperational ConsiderationsWater Resources ConsiderationsTarget

ILI Range



Technical Technical Performance Performance

CategoryCategory

250-500200-400150-300100-20050-1004 – 8B

250-500200-400150-300100-2004 - 8C

Litres/connection/dayLitres/connection/day(when the system is pressurised) at an average pressure of:(when the system is pressurised) at an average pressure of:ILIILI

> 1000> 800> 600> 400> 200> 16D

500-1000400-800300-600200-400100-2008 - 16C

< 250< 200< 150< 100< 501 – 4A

> 500> 400> 300> 200> 8D

125-250100-20075-15050-1002 - 4B

< 125< 100< 75< 501 - 2A

50 m50 m40 m40 m30 m30 m20 m20 m10 m10 m

Dev

elop

ing

Cou

ntr

ies

Dev

elop

ed

Cou

ntr

ies

World Bank Institute (WBI)



Real Loss Performance Categories

AA: Further loss reduction may be uneconomic : Further loss reduction may be uneconomic unless there are shortages unless there are shortages BB: Possibilities for further improvement: Possibilities for further improvementCC: Tolerable only if resources are plentiful and : Tolerable only if resources are plentiful and cheapcheapDD: Inefficient use of resources, indicative of : Inefficient use of resources, indicative of poor maintenance and system condition in poor maintenance and system condition in generalgeneral



WB-EasyCalc☺: A Free Multilingual Software



Interesting: The Philosophy

"Water loss reduction primarily has to be done for the "Water loss reduction primarily has to be done for the following reasons:following reasons:

HygieneHygieneEnsuring sufficient levels of supplyEnsuring sufficient levels of supplySafetySafetyEcologyEcology

and and ONLY ONLY in the case of high water losses there are in the case of high water losses there are also economic reasons for reducing them" also economic reasons for reducing them"



Apparent Losses

apparent losses should be assessed apparent losses should be assessed utilities without good data: use 1.5 utilities without good data: use 1.5 –– 2.0% of 2.0% of authorised consumptionauthorised consumptionsounds very low but might be explainable as sounds very low but might be explainable as follows:follows:

high accuracy customer metershigh accuracy customer metersregular meter replacement regular meter replacement water pilferage is not an issuewater pilferage is not an issuereliable meter reading, data handling and billing procedures reliable meter reading, data handling and billing procedures and systemsand systems



develop and implement a strategy that includes:develop and implement a strategy that includes:calculation of water loss levels and burst frequenciescalculation of water loss levels and burst frequenciesanalysis of water loss levels and their trend analysis of water loss levels and their trend (increase/decrease)(increase/decrease)reduction of awareness, location and repair timesreduction of awareness, location and repair timesactive leakage controlactive leakage controlrecord keepingrecord keepingasset management (network rehabilitation)asset management (network rehabilitation)

Chapter 6: Methods and Measures for Monitoring and Reduction of Real Losses



Sensational Recommendation for Germany: DMAs!

For the execution of real loss control For the execution of real loss control measurements, the distribution network has to measurements, the distribution network has to be split into small areasbe split into small areas

one (or more) inflow pipesone (or more) inflow pipessize shall be determined by the length of mains, size shall be determined by the length of mains, which shall be in the range of 4 to 30 kmwhich shall be in the range of 4 to 30 kmpermanent or portable flow meters shall be usedpermanent or portable flow meters shall be usedthe minimum night flow has to be establishedthe minimum night flow has to be established

dvgw-w 392 the german water loss guidelines · operating with system leakage above this level would...

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