There has been a lot of controversy about drinking alkaline water. Water has a natural pH balance (unattached hydrogen versus hydrogen and oxygen molecules) of around 7 on a scale of 1 to 14. Going too far on the scale in either direction can be dangerous.
The body's pH
One school of thought says that to live a healthier life, you should try to keep your body less acidic. But different parts of the body have different pH levels: the stomach is quite acidic, the intestines more alkaline. So, in effect, you can't bring your body into a pH balance without doing yourself some harm. Additionally, it cannot be accomplished by drinking alkaline water.
The dangerous part of drinking alkaline water are water ionizers. Supposedly, water ionizers change the pH balance of tap water and make it more alkaline. But generally speaking, these ionizers do very little to change the pH of the water, and do absolutely nothing to filter the water. When you use an ionizer alone, the water may not be properly filtered.
Drinking alkaline water also can negatively affect your stomach. The stomach produces acid to break down and digest food and drink. When you drink alkaline water, the stomach attempt to bring down the pH of the water. It does this by creating more acid, which can cause indigestion or complicate a condition such as an ulcer.
Metals are more highly concentrated in alkaline water. In lesser concentrations, these metals may not be a big problem, but concentrated metals can interfere with the functioning of the thyroid gland.
The ideal pH of water is roughly between 7.4 and 7.6. Drinking water should be filtered and treated, but water that is too acidic or alkaline can be harmful. Bottom line: Drinking natural water is best.