This barrio used to be part of Munting Tubig, another of Ibaan’s barrios. In the old days, it was typical of villagers to choose as their heads men who were believed to possess “powers,” those in possession of “anting-antings” or amulets. Among those chosen to become had of Munting Tubig was such a man named Agustin, presumably after whom this barrio was named. This barrio was established in 1862 and its original settlers were the Portus, Dalisay and Magnaye families. In World War II, the barrio was raided by soldiers of the Japanese Imperial Army. Many of the barrio’s men were killed and buried near the toilet of the barrio’s school. In 1949, the barrio was placed under military control by the Philippine Constabulary because some of its inhabitants were under suspicion of involvement with the communist Hukbalahap movement.
San Agustin is situated at approximately 13.8290, 121.1645, in the island of Luzon. Elevation at these coordinates is estimated at 134.5 meters or 441.3 feet above mean sea level.