John Duncan Watson (7 March 1860 – 1946) was a British civil engineer. Watson was born in Dundee, Scotland on 7 March 1860. He specialised in sanitation and was regarded as a pioneer in the development of sewage treatment. Watson was engineer to the and also General Manager to the . At Birmingham he was responsible for the construction of the first large-scale percolating filter plant, a complete departure from the traditional land treatment in use in the city and elsewhere. Other changes that he introduced, based on his work in Birmingham, were the separation of sludge digestion, the extraction of methane from sewage for use in power generation and the introduction of flocculation prior to the percolating filter. He drew up plans for sanitation works in the district of Aberdeen which inc