TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Properties: The bittern has a specific gravity of 1.2-1.4. Preferred Composition: The bittern has a concentration of 5-80 %, and the acid and/or salts has a concentration of 10-50 %. The solution includes 10 % bittern, and 2 % mixed mineral acids.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compounds: Sulfates are added to the mixed solution for water conditioning. Phosphate, citrate, and/or succinate are added to the solution for promoting growth of microorganisms, fishes, and plants.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The water purificant further comprises 10-20000 ppm of chitins or chitosans.    TECHNOLOGY FOCUS - BIOLOGY - Preferred Plants: A boiled aqueous extract or dried-up powder of water front plants is added to the solution. The water front plants can be Salix subfragilis, Alnus japonica, Ulmus Davidiana, Acer palmatum thunb, Fraxinus mandshurica, Juglans mandshurica, Ilex serato, Viburnum Opulus L., Hydrangea paniculata, Staphylea Bumald, Carex Thunbeigit, Carex curvicollis, Carex dispalata, Scirpus triqueter, Scripus triangulatus, Osmunda cinnamomea, Impatieus noli-tangere, Senecio pierotii, Lythrum anceps, Iris setosa, Phragmites communis, Zizania latifolia, Typha latifolia, Sparganium stoloniferum, Scirpus lacustris L., Nuphar japonicum, Nelumbo nucifera, Acorus calamus L., Iris pseudoacorus L., Meryanthes trifoliata, Trapa natans, Nymphoides peltata, Nymphoides indica, Nymphaea tetragona, Potamogeton destinctus, Euryale ferox, Brasenia Scheberi, Hydrocharis Morsus-ranae, Potamogeton crispus, Potamogeton malaianus, Potamogeton octandrus, Ophiopogon japonicum, Mynophyllum verticillatum, Ranunculus aquatilis, Najas marina, Vallisneria asiatica, Hydrilla verticilleta, or Mimosa. EXAMPLE - Formulated concentrate of water purificant was prepared by mixing 3 % bittern, 1 % mixed mineral acid solution, 1 % aluminum chloride, and 1 % ferric chloride. The solution was diluted 1000-10000 folds and added in the water supplying tank, cooling tower and humidifier. After then, 90 % of the growth of legionnaires was inhibited.