* Hypochlorous Acid (HOCl): Chlorine reacts with water to form hypochlorous acid (HOCl), which is a weak acid.

* Hydrogen Ions (H+): Hypochlorous acid releases hydrogen ions (H+) into the water.

* Lower pH: An increase in hydrogen ions in the water lowers the pH, making the water more acidic.

Here's a simplified explanation:

Think of it like this:

* Higher pH: More basic (alkaline) water has fewer hydrogen ions (H+).

* Lower pH: More acidic water has more hydrogen ions (H+).

Since chlorine releases hydrogen ions, it lowers the pH of the water.