Presented herein are membranes for use in separating solids including salts from water. One application of such membranes is in a sub-surface irrigation system that that utilizes a saline or tainted water as a feed source. In various embodiments, the membranes operate on a solution diffusion principle. In other embodiments the membranes operate on an ultrafiltration principle and/or a solution diffusion principle. In any embodiment, the membranes operate similar to pervaporation membranes suitable for non-pressure driven systems. The membranes are designed to provide increased flux rate while separating solids such as salts from water.