In June 1998, a regional rainwater harvesting workshop organized by the Regional Land Management Unit (RELMA) and held in Machakos, Kenya, conceived the idea of setting up a Southern and Eastern Africa rainwater harvesting network, to be called SearNet. At the time, delegates were drawn from Ethiopia, Kenya, Uganda, Tanzania, Zambia and Zimbabwe. A series of annual meetings then followed to determine the future of the network.

Uganda,Ethiopia, Zambia and Zimbabwe have since hosted the annual meetings in 1999, 2000, 2001 and 2002, respectively. At the meeting held in Livingstone, Zambia, in December 2001 declaration of intent was signed that paved the way for the process of registering SearNet as an international NGO.

In December 1999, RELMA, based in Nairobi, Kenya and the Centre for Science and Environment (CSE) based in New Delhi, India, jointly made a proposal to the Global Water Partnership (GWP) secretariat in Stockholm, Sweden, for a project entitled "A Network for Green Water Harvesting in Eastern and Southern Africa and South Asia". GWP approved the proposal and arranged for funding from the Netherlands Ministry of Foreign Affairs with co-funding from RELMA.

The programme is based at RELMA and began operations in June 2002. So far, the following national associations have been registered with SearNet:

the Kenya Rainwater Association (KRA),
the Botswana Rainwater Harvesting and Utilization Association (BORHUA),
the Ethiopia Rainwater Harvesting Association (ERHA),
the Rainwater Harvesting Association of Malawi (RHAM),
the Rainwater Harvesting Association of Rwanda (RRHA),
the Rainwater Harvesting Association of Tanzania (RHAT),
the Uganda Rainwater Harvesting Association (URWA),
the Zambia Rainwater Harvesting Association (ZAHRA), and
the Rainwater Harvesting Association of Zimbabwe (RHAZ).