Reverse Osmosis (RO) Membranes


Replacement reverse osmosis (RO) membranes

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 pressurized 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.

Changing the membrane itself is not a difficult task and can be performed in the field.

• 40” Membrane
• 21” Membrane

How to change the membranes


For the USA – the price billed on checkout will be the Landed Cost (includes freight, import duty and sales tax),

For all other countries – the price billed on checkout will be the item cost + freight rate only; the recipient will be liable to pay import duty and sales tax (if applicable) in their country.

Get your watermaker today!