since pre-colonial times, manila residents used the pasig river as their main source of water. the water was filtered through cloth in a "tapayan" (earthenware cooling jar) and then cleansed with alum. according to josé rizal, the rivers and "esteros" in binondo were used as bath, sewer, laundry, fishery, transport and even drinking water. this can be one of the reasons for water-borne epidemics during those periods.