Reverse Osmosis Contaminant Rejection

Sodium
Calcium
Magnesium
Potassium
Iron 2
Manganese 2
Aluminum
Copper
Nickel
Zinc
Strontium
Cadmium
Silver
Mercury
Barium
Chromium-6
Chromium-3
Lead
Chloride
Bicarbonate
Nitrate3
Fluoride
Phosphate
Chromate
Cyanide
Sulfate
Boron
Arsenic + 3
Arsenic + 5
Selenium
Radioactivity
-----------

Bacteria
Protozoa
Ameobic-
Cysts
Giardia
Asbestos
Sediment/
Turbidity

Organic
Contaminants
Organic
molecules with
a molecular
weight < 300

Organic
molecules with
a molecular
weight < 3005

90-95%
93-98%
93-98%
90-95%
93-98%
93-98%
93-98%
94-99%
93-98%
93-98%
93-98%
93-98%
93-98%
93-98%
93-98%
94-99%
94-99%
94-99%
90-95%
90-95%
85-90%
90-97%
93-98%
90-95%
90-95%
93-98%
55-60%
70-80%
94-99%
93-98%
93-98%
--------

> 99%
> 99%
> 99%

> 99%
> 99%
> 99%
> 99%

> 99%

0-99%

1. This table of nominal rejection performance is for reverse osmosis membranes used in drinking water systems operating at a net pressure (feed pressure less back pressure and osmotic pressure) of 60 psi and 77° F water temperature.

The actual performance of systems incorporating these membranes may be different due to changes in feed pressure, temperature, water chemistry. contaminant level, net pressure on the membrane, and individual membrane efficiency. Countertop RO drinking water systems produce better overall rejection performance than under-counter systems due to maximizing of net pressure on the membrane.

2. While iron and manganese are effectively removed by the membrane, they also can easily foul its surface with deposits even at low concentrations. Generally, iron and manganese should be removed by other water treatment methods prior to RO treatment.

3. Nitrate removal depends on factors such as pH, temperature, net pressure across the membrane. and other contaminants present.