The concept of the unified membrane fouling index (UMFI) was introduced recently for assessing the fouling of low pressure membranes (LPM) used in water treatment. The major advantages of the UMFI over most other fouling indices are the universality (independent of filtration scale or mode) and specificity (based on the actual membrane of interest for full-scale application). This study applied the concept of the UMFI to the assessment of fouling results obtained in a bench-scale fouling study. This study was conducted with combinations of four commercially available LPMs and four natural waters (including secondary wastewater effluent) under systematically varied hydrodynamic conditions. It was found that, with the adoption of the UMFI, the fouling potential of different membrane and water combinations can be presented in a unified, concise, and quantitative way, enabling quantitative and integrated assessment of the fouling data and their relationships with different potential fouling factors. Expansion of the UMFI concept to other studies is anticipated to assist in the integration of the vast amount of bench-scale fouling results obtained with different LPMs; this integration is crucial to the mechanistic understanding of LPM fouling. (C) 2009 Elsevier B.V. All rights reserved.