George Walker Herdman, civil engineer, was the son of Robert Herdman and his wife Emma Catherine Abbott. He was educated at the University of Edinburgh, where he was awarded the degrees Bachelor of Science (BSc) and Master of Arts (MA). He was an associate member, and from 1906 a member, of the (British) Institution of Civil Engineers. In 1896 he came to South Africa and was engaged in surveying and constructing waterworks for Cape Town, Bloemfontein, Johannesburg and other municipalities. Returning to Britain in 1899, presumably to avoid the effects of the Anglo-Boer War (1899-1902), he worked on the waterworks of Edinburgh, as resident engineer at the Warrington waterworks (1900), and as assistant engineer for the East London (England) Waterworks Company (1901-1903). A paper by him on "An improved form of joint for the Scotch levelling staff, and a new system of graduation", read in 1900, was published in the Transactions of the Royal Scottish Society of Arts (1903).
In 1903 Herdman came to the Transvaal Colony and in September that year entered its Department of Irrigation and Water Supply as waterworks engineer. He was promoted to executive engineer in July 1904 and two years later published an article on "Irrigation enterprise in the Transvaal: Buffelspoort, Rustenburg District" in the Transvaal Agricultural Journal (1906, Vol. 4(14), pp. 311-314). In March 1907 he was transferred to the Public Works Department as inspecting engineer. After the formation of the Union of South Africa in 1910 he held the same position in its Public Works Department. He was appointed assistant director of irrigation in 1917 and two years later as acting director during the absence of the director, F.E. Kanthack*.
In 1902 Herdman joined the British Association for the Advancement of Science. By 1906 he was a member also of the South African Association for the Advancement of Science. At its annual meeting held in Kimberley that year he read a paper on "Water rating", which was published in its Report for 1905/6 (pp. 420-439). He served on the association's council as one of the representatives of Pretoria in 1907/8 and again in 1909/10. In 1913 he was a member of the South African Society of Civil Enginees and served on its council for that year.