PURPOSE: To obtain an unglazed ceramics capable of obtaining ecological water by calcining a formed body contg. specified Palaeozoic clay and monazite in a reducing atmosphere.

CONSTITUTION: The cylindrical formed body with the Palaeozoic clay (a) contg. a fossil bed consisting essentially of diatomaceous earth and monazite (b) as the effective components is calcined at 700-1100°C in a reducing atmosphere to obtain a ceramic contg. metallic iron. Raw water is pretreated with this unglazed ceramic, then treated with a reverse-osmosis membrane or ultrafiltered and then contact-treated with the unglazed ceramics. Consequently, novel water excellent in quality, high in physiological activity, compatible with living bodies, capable of imparting various chemical and biochemical characteristics and appropriate for ecology is obtained. Besides, the Palaeozoic clay is the clay collected from the bed formed some 5.7×108 to 2.4×108 years ago, and contains the fossil bed and a relatively large amt. of iron.