Natural alkaline water is generally considered safe to drink as it contains water and minerals. Artificial alkaline water should be drunk with caution, as it likely contains less of the minerals necessary for good health, and overingestion could cause deficiency in those minerals.
Water naturally becomes alkaline when it runs over rocks and picks up additional minerals, which change the pH level. Alkaline water can also be made at home by adding lemon or lime juice to distilled water. While alkaline water is generally considered safe, medical professionals warn against using it as a treatment for any condition as there is not enough scientific evidence to support health claims.