A 'think tank' comprising representatives of academic institutions, non-governmental organisations and experts has been formed to study the impact of water and sanitation problems on the economy and health of underprivileged especially in suburbs. The think tank is the outcome of a workshop conducted by the Citizens' Alliance for Sustainable Living (SUSTAIN) earlier in July. M.G. Devasahayam, Managing Trustee of SUSTAIN, said the salient points of the discussions would be forwarded to authorities.