50 gpd Low-Pressure Membrane


SKU: lp-membrane Category:

These are the membranes we use in our Counter-Top Reverse Osmosis Systems, specifically because of their “Low Pressure” specification, and are drop-in replacements for membranes in residential and growers’ systems.

Most residential-type RO membranes are rated at 77°F and 65 psi water at the membrane.  Most homes have water pressure between 45 and 80 psi, but once it runs though your pipes and tubing to the RO system, it is greatly reduced, and most of the country does not have 75° water.  Both reductions negatively affect the output efficiency.

For example, a standard 100 gpd system is specified to consume 400 gallons of water per day, yielding 100 gallons of purified water and 300 gallons of flush water, or a pure:input ratio of 1:4.  If the feed water is 65°F and 50 psi, the output of that 100 gpd reverse osmosis system will be about 60 gpd, while the volume of “flush” water is unchanged, greatly reducing the overall efficiency to 60:400 or 1:6.7.

These low pressure membranes are rated at the same 77°, but at 20 psi water pressure, so are specified to provide 50 gallons of pure water and 80 gallons of flush water per day, a 1:2.6 ratio.  Better yet, if that membrane is employed with the same 45 psi & 65° input water as the example above, its output will actually be increased to about 55 gpd, increasing the efficiency to 1:2.45.

Price includes an appropriate flow restrictor and shipping to US addresses.