SuSanA came into existence in early 2007. Its creation was motivated by the UN’s decision to declare 2008 as the International Year of Sanitation (IYS). In 2006, GIZ together with several other organisations took the initiative to form a task force to contribute to the promotion and up-scaling of sustainable sanitation.
In January 2007, a first meeting in Eschborn, Germany, resulted in a large number of commitments by the participants from various organisations. The minutes of the very first meeting are available here. At that meeting, the first draft of a "joint road map for the promotion of sustainable sanitation in IYS 2008" was developed.
In order to have a joint label for the planned activities, and to be able to align with other potential initiatives, the group gave itself the name "Sustainable Sanitation Alliance (SuSanA)".
In January 2017, SuSanA celebrated its 10-year anniversary, see here.