What is the Fourth Phase of Water? Dr. Gerald Pollack
Natural filter components include 1.) toxin removal-purification, 2.) re-mineralization / ionization and restoration of natural electro-magnetic energy fields. Elements include: purifiers, ionizers, high carbon content, shungite stone, magnesium oxide clay, maifan stone and more. This is just a start.
...Peter the Great set up Russia's first spa in Karelia to make use of the water purifying properties of shungite...He also instigated its use in providing purified water for the Russian army. The anti-bacterial properties of shungite have been confirmed by modern testing.[ Wikipedia, Medical Geology in Russia and NIS p. 223. ISBN 9789048134298]