This paper describes a series of tests set up in each of the Company's three divisions designed to compare active and passive methods of leakage control and to determine the economic effectiveness of testing waste districts. Each division adopted a different frequency for monitoring leakage to include monthly, bi-monthly, and quarterly testing, with one of the test areas within each division being subjected to an active leakage control programme and the other area monitored using passive leakage control only. The paper summarizes the results of the field trials carried out since 1981 and reviews existing Company policies.