What is the PH of reverse osmosis water tap water?

Answer 1

The Ph of water, whether it's reverse osmosis water or normal water, will be 7 or extremely close to 7. RO water is simply cleaner than normal because it has passed through special membrane filters that filter out molecules larger than water (H20), but it's still H2O. PH simply means the power of hydrogen and is not really affected by the cleanliness of the water. so the answer would be PH7 witch is also in the middle of been acid or alkali.

Wrong answer. ph is greatly affected by the "cleanliness" of water. All of the chemicals or materials in the water greatly affect ph. Pure water should be slightly greater than 7.0. When using a reverse osmosis system it reduces the contaminants (anything other than water) but it also will tend to lower the ph to around 6. It also reduces the oxygen in the water so it is not 100% saturated by less. One should use a filter to bring the ph back to around 7 for water when using RO.

Really, both of these answers are less than 100% accurate. Reasonably pure water in a normal room will have a pH of around 6. This is due to carbon dioxide dissolving in the water to create carbonic acid (H2CO3). While reverse osmosis will remove most of the larger ions, if you leave the water out in the room it will dissolve carbon dioxide from the air. While pure water with absolutely ZERO dissolved gases will have a pH of 7, this is rarely achieved in an open air room unless you heat the sample to drive off the gas.

In addition, some smaller ions will still be present in the reverse osmosis water and these ions can have acidic or basic properties.