A desalination unit for production of potable water from sub-soil brine including in combination a trapezoidal basin, a condenser, a feed tank, a header, a heat exchanger, a flush valve, a sprinkling system, exhaust heat pipe and water collecting channel; where the exhaust heat pipe is connected to a heat source at one end and to the header at the another end, the header being coupled with the heat exchanger to provide the heat flow, and the heat exchanger being fitted at the inner portion of the trapezoidal basin to heat the sub-soil brine.