How is the bottled water in the water dispenser bubbling in summer? Can I drink?

In summer, it is normal for bottled water in drinking fountains to bubble, and the water is drinkable.

Bubbles on the barrel wall indicate that the barrel is clean, because the barrel is plastic, and the clean plastic surface is not easy to dissolve with water.

Manufacturers produce bubbles when adding water. Some bubbles are attached to the barrel wall, and some are absorbed by water. The barrel escapes by shaking the bubbles on the barrel wall. At this time, there are no bubbles in the barrel wall. After standing, due to the temperature rise, bubbles in the water come out and attach to the barrel wall.