Rainman 21" RO Membrane

Replacement 21" x 2.5" Reverse Osmosis Membrane

The membrane is a key part of your watermaker, and is at the core of the desalination process. This component extracts the potable fresh water from the filtered and pressurised seawater stream. When well cared for, the membrane should last five to ten years. The important aspect to be aware of is that you do not want small organisms in the seawater dying and rotting in your membranes.

As your membranes age, the TDS (total dissolved solids) will gradually increase. Most people will change membranes when the TDS readings get to 700-800 parts per million (ppm).

Although the membrane could be considered a long term consumable, we generally do not recommend customers keep a spare on board. Failure is extremely rare and membranes have a limited shelf life when new. Rainman uses Filmtec SW30 membranes, either SW30-2540 (2.5″ x 40″) or SW30-2521 (2.5″ x 21″). These are standard sizes and can be easily acquired around the world.