A porous grog with a body composition of water, clay and combustible material. Further, an earthenware water purification filter utilizing the porous grog in the body composition of the filter. Further, an earthenware filter utilizing silver chloride treatment for water disinfection is disclosed. A water purification system incorporating said filter, said water purification system capable of removing about 99% of all particles not less than 1.0 micron is size, and removing virtually 100% of fecal coliform indicators. In other embodiments, methods of disinfecting pottery toilet liners including various open surfaces using silver chloride treatment are disclosed.