William Reid Bell (sometimes Reid-Bell), son of Robert Fitzroy Bell and his wife Christina Ker Reid, emigrated to New Zealand when barely out of his teens and was apprenticed to his cousin, the harbour engineer C. Napier Bell. Early in 1885 he was appointed resident engineer for the construction of a breakwater at Burnie, Tasmania, and subsequently was put in charge of various other harbour works on the north-west coast of Tasmania. Around the middle of 1888 he returned to Britain to work for his brother, who held the controlling interest in a big shipbuilding firm. He was a Fellow of the Royal Meteorological Society and a member of the (British) Institution of Civil Engineers.
In 1898 Bell was living in Durban, where he submitted a design for a bridge over the upper Tugela River to the Public Works Department of the Natal Colony. He served as an officer during the Anglo-Boer War (1899-1902). By 1903 he was practising as a consulting irrigation engineer in Potchefstroom and had become a member of the South African Association for the Advancement of Science. At the association's second annual congress, held in Johannesburg in 1904, he read a paper on "Some considerations respecting irrigation in the new colonies" [Orange River Colony and Transvaal Colony], which was published in the association's Report for that year (pp. 383-387). By 1906 he had moved to Johannesburg and was a member also of the Geological Society of South Africa. The next year he again read a paper at the annual meeting of the South African Association for the Advancement of Science, entitled "Notes on the rainfall in forest regions" (Report, 1907, pp. 32-33). He was still a member of the association in 1911, but had left South Africa for a post in the Public Works Department in Sydney, Australia.
In 1912 Bell was again engaged as resident engineer for the construction of a breakwater at Burnie. He also did railway survey work and for a time acted as government hydraulic engineer to collect data prior to the inception of the Great Lake scheme. During these years he delivered a paper on the improvement of the port of Melbourne (1911) and a lecture on the Burnie harbour and breakwater (1924), before the Victoria Institute of Engineers. He was married twice, first to Sarah Roberta Gibbon, sister of a premier of Tasmania, with whom he had two sons and a daughter. After her death he married a miss North.