Microbiological evaluation of drinking water construction materials--comparison of two test procedures.

Materials used in contact with drinking water can impair water quality by supporting the growth of aquatic microorganisms. In order to prevent this problem several different test procedures have been developed but to date no comparative study of the performance of these methods has been published. During collaborative studies between the regional laboratories of the Thames Water Authority, London, and the Institute of Hygiene, University Bonn, duplicate samples of 11 PVC materials were exchanged and evaluated by the standard methods used in the United Kingdom (UK) and the Federal Republic of Germany (FRG). There was a good agreement between the results as assessed by the published criteria. When a stricter criterion for interpreting the results of the UK method was applied to the findings, a complete agreement between the methods was observed.