The River Medway and its tributaries and sub-tributaries have been used for more than 1,150 years as a source of power. There are over two hundred sites where the use of water power is known. Many different processes were performed by the use of water power:- corn milling, fulling, paper making, iron smelting, pumping water, making gunpowder, vegetable-oil extraction, and electricity generation. Today, there is just one watermill working for trade. Those that remain have mostly been converted. Such conversions include a garage, dwellings, restaurants, museums and a wedding venue. Some watermills are mere derelict shells, lower walls or lesser remains. Of the majority, there is nothing to be seen. A large number of tributaries feed into the River Medway. The tributaries that powered watermills will be described in the order that they feed in.