Austrian ILIs

ILIs in Austria – update 2015

Following several years research and trials into the application of the ILI within Austria, OVGW re-issued their W63 Guideline in 2009 with ILI as the decisive real losses performance indicator (Paper 2009T). During the OVGW trials, some ILIs less than 1.0 were reported, and although some of these were later identified as having systematic water balance errors (for example unmetered public fountains), it became clear that ILIs less than 1 were occurring in some small Austrian systems.

Austria has around 5500 Water Utilities, with around 5000 of them having less than 3000 service connections, which is the generally recommended lower guideline limit at which some assumptions used in UARL and ILI calculations may cease to apply. Such systems would be classified as ‘Very Small’ in EU Good Practices on Leakage Management (2015).

Recent studies (Paper 2014N ; Presentation 2014 M CS1) using component analysis and pressure:leak flow rate and pressure: bursts prediction methods have identified the reasons why ‘Very Small’ Utilities can achieve annual leakage lower than the UARL formula (ILI less than 1.0).

ili a 1

Selected small system ILIs (original data source: OVGW benchmarking)

Source: Austrian Small Systems Case Study in

Good Practices on Leakage Management – Case Study document._Final.pdf

Having established the factors which can result in ILIs less than 1 in well managed ‘Very Small’ systems, the next step was to gather and review an ILI data set for ‘Small’ and ‘Medium’ sized systems with 3000 to 300,000 service connections.  OVGW kindly provided anonymous ILI data with average pressures from their 2011 survey, as shown below. Because of the varied topography and generally high quality of design and construction standards for infrastructure in Austria, pressure management is not as widely practiced for management of Real Losses as in other European countries.

li 4

The ILI ranges in Categories A to D in the above bar chart are those used in EU Good Practices on Leakage Management (2015) and the OVGW W63 descriptions for these Classes are shown in the Table below.

ILICLASSEVALUATION
<2 AVERY LITTLE TO LITTLE WATER LOSSES, further reduction could be counter productive; further analysis before any action should be executed.
2 to 4 BMEDIUM WATER LOSSES, potential for noticeable loss reduction existing, improvement in leakage control and infrastructure management.
4 to 8 CHIGH WATER LOSSES, volume and reasons for losses have to be analyzed and attempts to reduce the volume of lost water has to be intensified.
>8 DVERY HIGH WATER LOSSES, volume and reasons for losses have to be analyzed, distinct leakage control and leakage reduction has to be executed immediately.

Table: Descriptions of Austrian OVGW categories Performance Bands A to D,

from OVGW 63 (2009)

Acknowledgements and thanks: to OVGW (Mr. Manfred Eisenhut) for approving the publication of this data; to Daniela Fuchs-Hanusch for preparing the data, and to Joerg Koelbl for ongoing guidance in understanding and interpretation of Austrian leakage management.

Future Updates: Countries in Europe and elsewhere which already have sufficient ILI data to justify a separate Webpage within Global ILIs are also invited to Contact ILMSS Ltd. European Utilities with reliable calculated ILI values wishing to be represented in future summaries of European ILI on this website are also invited to Contact  ILMSS Ltd.