Fargus was born in Hong Kong to a Scottish father and Australian mother and therefore holds dual British-Australian citizenship. After spending 10 years in Hong Kong, she moved to the UK for boarding school (Millfield) for five years before transferring to Australia where she completed high school at Somerset College in Mudgeeraba, Queensland. She then moved back to England, where she swam full-time at the University of Bath.[3] In 2002, she enrolled at the University of Southern California (USC) on a full athletic scholarship and until 2006 competed and worked as a volunteer coach in the United States. She was voted USC Woman of the Year 2005 and graduated cum laude with a bachelor's degree in communication. All those years she represented England and Great Britain at international competitions,[2] after which she transferred her sporting allegiance to swim for Australia. From January 2006 to March 2008 she competed for Australia, winning the 200 m backstroke event at the 2006 Commonwealth Games.[4] An Australian postal stamp featuring her has been issued on this occasion.[5]
Around March 2008 she retired from swimming and moved back to Hong Kong, where she first worked as an account executive at PPR Greater China and then as media relations manager at HSBC.[4]