As a measure of reducing the foreign trade deficit and to augment the usable land for commercial plantations, nineteenth century British authorities attempted to restore the irrigation system that prevailed in Sri Lanka since the Early Historic Period. In so doing, neither the system components were subjected to any hydraulic engineering analysis nor the entire systems were studied in a holistic context. The open well structure, called bisokotuva, of the ancient sluices was interpreted as the equivalent of the modern valve pits. With this understanding, ancient sluices were restored by installing the flow control gates inside the bisokotuvas. This article argues that such understanding was not based on the actual physical remains of the ancient works but was due to the colonial precept of controlled flows of irrigated water. It also discusses similar cases in several other Asian countries and how such assertions affected the European understanding on the Asian societies.