In drinking water treatment flow fluctuations or surges can occur at the filtration stage. Pilot plant tests were carried out to investigate the impact of flow surges on filter performance in this study. Moreover a filtration model was applied to analyse the impact of flow surges on filter performance and predict the experimental data obtained from pilot plant tests. Experimental results showed that flow surges caused an increase in effluent particle concentration and head loss. Theoretical analysis in this study showed that the impact of a flow surge became more significant as the filtration run approaches the particle breakthrough stage. The model was also used to fit the data from one water treatment plant. The comparison demonstrated a good agreement.