Abstract: A portable solar still, controlled by a sun actuated mechanical valve, including a thermally insulated evaporation chamber structure within which distillation takes place, is assembled from sidewall panels and floor panels of foam plastic thermal insulation, these panels being strengthened and made into rigid structural units by metal tubes or rods incorporated internally into the foam plastic panels,a transparent cover sealing the sloping top of the evaporation chamber including a transparent, flexible, plastic film which is stretched across, and has its four boundary edges attached to, the four members of a closed rectangular frame of slender metal tubes,wick matting, disposed on the floor of the evaporation chamber including a layered mat of fine, randomly oriented,.

Abstract: A valve is provided for precisely controlling fluid flow at low flow rates and simultaneously filtering said fluid. The valve employs a resilient porous filtering medium interposed in the flow path and capable of undergoing adjustable compression by means of a threaded shaft associated with an external handle. When the filtering medium is compressed, it provides greater occlusion of the flow path, thereby diminishing flow rate through the valve. The valve is readily dismantled to facilitate cleaning or replacement of the filtering medium.