Membrane systems remove the minerals in the water. The pressurised housings are 6 meters long. The total purification surface area is 40,000 m2, which is about eight football pitches in size. During the purification process, 20% concentrate flows continuously to the surface water. An anti-scaling medium is added to prevent fouling of the membranes. Reverse osmosis is a two-step process with two systems working in series.