From 1851 to 1875, Greaves was the Chief Engineer to the East London Water Company.
At the expiration of his pupilage, in 1837, he was for a short time employed in the office of his uncle, Mr. William Chadwell Mylne, at the New River Head.
He was instrumental in the development of the Company’s station at Lea Bridge. Greaves supervised the construction of filter beds at Lea Bridge; the large Cornish engine called the 'Victoria'; the aqueduct from Walthamstow; and erected the 'Prince' and 'Princess' engines.
He challenged well founded accusations that the East London Company was the source of cholera outbreaks in 1866. Greaves’ work brought constancy, reliability and capacity to water supply.