Pure RO water usually has a pH between 6.0 and 6.5—slightly acidic. That might sound scary, but hold your horses! It’s not the same as battery acid (phew!).
The acidity comes from the RO process itself. It strips away almost everything—minerals, contaminants, and even the buffers that keep pH stable. Without those buffers, the water is like a blank canvas, easily influenced by the air around it.
Why So Acidic? The Science-y, Yet Fun Part
Here’s the cool part: once that pure water hits the air, it absorbs carbon dioxide (CO₂). Think of it as your water taking a deep breath! That CO₂ forms a tiny bit of carbonic acid, which drops the pH.
It’s a totally natural reaction. If you test RO water immediately after it’s made (in a closed system), it can be closer to neutral (7.0). But wait a minute, and it dips to that slightly-acidic zone.
So really, the pH isn't a flaw—it's just your water showing off how pure it is! It’s like the water is saying, “I’m too clean to hold my own pH right now.”
