A laboratory scale flexible rubber blade water wheel has been investigated at the hydraulic laboratory of University of Southampton. The effect of channel width on water wheel performance has been studied. Different upstream and downstream channel widths are set for the tests. In this paper, the experimental set up, tested water wheel and the measurement procedure are described and the experimental results are shown. Results show significant improvement in power output and efficiency in reduced channel width. (C) 2012 Elsevier Ltd. All rights reserved.