Born in South Africa, Daniel Tailliferre Hauman (DTH) van der Merwe began playing at age five. He later made the Boland Under-16 team.
In 2003, the van der Merwe family immigrated to Regina, Canada where DTH attended Dr. Martin Le Boldus High School. He made the Saskatchewan U18, U21 and Rugby Canada Super League Prairie Fire teams.
In 2005 van der Merwe moved to Victoria, where he played for James Bay AA.
In 2006, van der Merwe made his debut a substitute against Barbados in the RWC qualifier, scoring two tries. That same year, van der Merwe was a member of Canada’s November tour to Wales and Italy.
He started in all four games of the 2007 Rugby World Cup - scoring a try against Japan.