DIY RO watermaker


New member
5 May 2004
I've searched for info on diy reverse osmosis for water makers and found little specific info. I understand the principle, but need some hard facts on sourcing parts, requirements etc.

I have found reference to the use of power washer pumps and a suitable manufacturer of these pumps, but little else. There is one chap out there offering his own information, for a price, but I have no idea if this is of any use.

Anyone know a source of information on the actual construction of these, or better still any experience?



New member
19 Dec 2004
I had to troubleshoot my Powersurviver at the entrance to the Red Sea and I spend many, hours taking it apart again and again until I understood the working. (and temporarily fixed the membrane with Araldit)

The membrane is the most important part. It consists of a special plastic material, 30 cm wide, with some spacing material between, rolled up on and glued to a plastic tube. This plastic tube has many small holes in it. Thats where the fresh water is coming out. Bigger units have more then one such tube, connectetd together. The high pressure pump is pressing water inside this rolled up plastic material. The material is "leaking" the water without the salt down to the small holes and finally into your tank.

There are two systems: rotary high pressure pump and piston type pressure pump. The Powersurviver uses a piston type pump, consuming in the range of 100 Watt (8 Amps @ 12V) for +- 10 Liter water per hour. The brine is reused, to save on energy. A very clever design is leading the brine from the membrane back to the piston and recycling some of the power still in it. The electric motor has only to generate the delta pressure from what is lost on the drinking water side. The pump consists of two valves, a piston and a rod with a couple of O-rings, to regulate the flow of the brine to the back of the piston. No springs, all in stainless steel. With a bag of O-rings, nothing can go wrong.

The membranes are mounted in an aluminium tube, with double O-rings on both sides of each membrane. The aluminium tube is also sealed on both ends with a plate with an O-ring. The Powersurvivor has a safety valve, but no pressure regulating. If the saltwater gets more saltier, it just runs slower, because the pressure is higher. All the rotary pumps I have seen use a pressure regulating armature.

The watermaker with a rotary pump is not using a powersaving setup. It produces much more water, but usually consumes in the range of 2 KW and is mostly driven by a large electric motor. Without a genset difficult to use.

Do you have found a source for the membranes ?