Type X-20 water tenders first entered service in 1956, as auxiliary water tenders to the second batch of Class GMA 4-8-2+2-8-4 Double Mountain type Garratt steam locomotives which entered service on the South African Railways in that year.

[1][2] The Type X-20 water tenders were built by the South African Railways (SAR) in its Pietermaritzburg shops between 1956 and 1958.

[1][3][4] Altogether 95 more Class GMA Garratt articulated steam locomotives with a 4-8-2+2-8-4 Double Mountain type wheel arrangement entered service on the SAR between 1956 and 1958.

[3][4][5] Only the second and third batches of Class GMA locomotives, 95 in total and numbered in the range from 4051 to 4170, were equipped with Type X-20 water tenders upon entering service.

[3][4][6][7] After the end of steam operations in the late 1980s, most of the watering facilities which once existed country-wide have either fallen into disuse or been removed.