"rmcinnis" wrote in message
...

Actually you only need 800 PSI

You can certainly do it with far less than that. A home RO unit runs off
the
water line pressure, which is usually less then 75 PSI.


Osmotic pressure is directly related to the concentration of salts in the
water. Tap water has a maximum concentration of 200 PPM salt so that the
pressure is about 10 PSI. Seawater OTOH at 36,000PPM salt and 68F has an
osmotic pressure of about 376 PSI. That is just enough pressure to STOP the
osmosis of salt into the low concentrate side. To REVERSE the osmosis
requires more pressure. Generally double or about 750 to 800 PSI.

(When you build your own watermaker you learn a lot of normally useless
stuff. :-) )

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
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