For most people, plain water is best.
Because alkaline water has a higher pH level than does plain tap water, proponents say that it can neutralize acid in your bloodstream, boost your metabolism and help your body absorb nutrients more effectively. Some even say that alkaline water can help prevent disease and slow the aging process. However, researchers haven't verified these claims.
Some studies suggests that alkaline water may help slow bone loss, but further investigation is needed to determine if this influences overall bone mineral density and if the benefit is maintained over the long term.