How to build your own marine reverse osmosis (RO) watermaker also known as a salt water desalinization plant.

This is a working document as I pull together the resources. So use the information at your own risk.

The core is Filmtec SW30-2514 or a Filmtec SW30-2521 membrane. The 2514 is 2.5" x 14" and can flow 150 GPD (Gallons Per Day) while the 2521 is 2.5" x 21" and can flow 300 GPD. These are the published specs. I am looking at these small sizes as I would like to build a high pressure pump that can be supplied by a 12V system. I would rather use solar and wind to generate electricity and therefore would rather let the water maker run all day than just for an hour or two on a generator. Another document that I have read by Anna Kieniewisz dated March 2006 seems to indicate that a 2 membrane system will perform better than a single and it also appears that reverse osmosis systems run better when used more often.

If I use the 2514 then it indicates that I will need an 800 PSIG (55 BAR) pump. On Lee Litchfield's web site he recommends CAT and Wanner Pumps. CAT states that its pumps are 85-95% efficient while Wanner says its pumps are 80-85%. Running some numbers here if I use the ... I really need a spreadsheet on this one. The number of variables are tremendous. Need to start with optimal membrane flow tied to a pump and then to a motor to get amp hours used per gallon... Thats it...


I read on the Cruisers forum that 225 PPM is the goal for desalinization based on test from a Spectra watermaker.