Strictly speaking, a reverse‑osmosis membrane itself cannot change the pH value of your incoming‑feed water. In other words, the pH of its product‑water should stay the same as that of the original feed‑water.

Tap water supplied by city public water systems that most people drink is generally weakly alkaline, with its pH ranging from 7.2 to 7.8. Then you may wonder whether its pH stays unchanged after being filtered by the reverse‑osmosis membrane.

The answer is no. Its pH usually falls between 5.5 and 6.5.

Here is the reason for this phenomenon. Carbon‑dioxide always exists in the surrounding air. It reacts with water and forms carbonic acid, and this substance brings down the water‑pH.

Up to now, no well‑known research has proven whether long‑term intake of weakly‑acidic drinking water does harm to human bodies. Anyone who carries out related studies can share your opinions with us.