StatisticalModelling of Water Main Failures

ReportNo WSAA 33

November 1991




UWRAAresearch project No. AM-11 Statistical Modelling of Water Main Failuresrequires an investigation of the Sydney Water Board’s watermains and mainbreaksdatabases and the trial application of an assessment methodology reported byMarks, Andreou, Jeffrey, Park and Zaslavsky from the Massachusetts Institute ofTechnology (MIT), 1987, which uses a survival model.


Afterclose examination of both databases it was discovered that informationavailable, particularly with regard to surviving pipe asset details, was notsufficient to allow the survival model to be used.


Itwas therefore necessary to use another method of analysis. Through the analysisof break rates, defined as the number of failures per kilometre, it has beenpossible to demonstrate the statistical association between aggressive soilsand the expected life of water mains.


Copiesof the Report are available from WSAA, price $A30. Orders may be placed throughthe Bookshop at or by email to