Does Reverse Osmosis affect pH?

pH is a measure of the acidity of water. We humans drink a variety of different beverages with varying pH ranges, from highly acidic orange and apple juice (3.3 pH), to mildly acidic milk and coffee (6 pH). Liquids that have a 7.0 pH are considered neutral and anything above that is alkaline.

Water can be acidic or alkaline, depending on the source.  In my view the ideal drinking water is a pH of about 7.4.

Reverse osmosis water purifiers will reduce the pH of drinking water.  Because reverse osmosis removes the minerals in water the water will then react with carbon dioxide upon exposure to air to form carbolic acids, thus lowering the pH.  The resultant pH will depend on the initial water chemistry. It cannot be predicted.

Reverse osmosis drinking water will tend to taste crisp, some people would say metallic.  I add a calcite filter to my systems to raise the pH and add a taste resembling spring water.

Some people object to drinking reverse osmosis water because it does remove minerals but in many instances reverse osmosis is the healthiest choice.  Please see my article on Minerals in Water.

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About James McMahon

Studied ecology at the University of Illinois, mountain survival at Eastern Washing University, Deep Ecology at Naropa, River Ecology with The Nature Conservancy and Luna Leopold
This entry was posted in Healthy Drinking Water, Reverse Osmosis, Water Purification. Bookmark the permalink.

One Response to Does Reverse Osmosis affect pH?

  1. Norman Silva says:

    FYI. The term carbolic acid can refer either to the pure compound, or to a solution in water. It is a weak acid, dissociating into the phenoxide anion and hydrogen cation only to a limited extent in aqueous solution. Carbolic acid should not be confused with carbonic acid, which is the weak acid formed when carbon dioxide dissolves in water.

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