The pH level of distilled water is 7.0 because it's neutral. It's not true what a "renowned online doctor" says that distilled water can turn acidic by absorbing carbon dioxide from the air. The air is composed of 78.9% nitrogen, 20.95% oxygen, 0.93% argon and only a very small 0.038% carbon dioxide and the balance is the other minor elements. If distilled water would absorb these elements, why not absorb oxygen and we can say we need the oxygen in our body. But he said that the distilled water absorbs CO2 that makes the water acidic. Not true! In any case, these elements have no pH value to them, so we cannot say that they would turn the water acidic.
I want to reiterate the danger of drinking alkaline water. I see many of my clients receive healing through drinking many liters of fresh fruit/vegetable juices daily through juice fasting/feasting.
On the other hand, there are a few who reported being severely sick after drinking many liters of alkaline water. This is an alkalosis condition. Note that ionized alkaline water often measure about 9-10 on the pH value chart which is highly alkaline. Some of the symptoms of alkalosis are: diarrhea, stomach cramps, vomiting and severe headache. In severe cases, brain chemistry is altered that leads to confusion, disorientation, hand tremor and muscles twitching.
Do your own research, think logically, and make your own informed decision about what's best for you.