This research project will be conducted in nine (9) municipalities (Akbar, Tuburan, Mohammad Ajul, Tipo-Tipo, Albarka, Ungkaya Pukan, Sumisip, Maluso, and Lantawan) and one (1) city (Lamitan City) of Island province of Basilan, BARMM. The study focuses on assessing the groundwater quality for drinking by comparing the concentration parameters with the standard guidelines of the World Health Organization (WHO) and Philippines National Standard for Drinking Water (PNSDW), computing the groundwater quality index (GWQI), and Groundwater Quality Index for Saltwater Intrusion (GQIswi). GIS software will be used to create spatial distribution maps which identify the boundaries of each parameter’s concentration. Groundwater samples will be taken from the existing wells, 9 sampling wells each for Lamitan City and Sumi sip, six (5) sampling wells each from (Akbar, Tuburan, Moh. Ajul, Tipo-Tipo, Albarka, and Ungkaya Pukan), and seven (6) sampling wells each from Maluso and Lantawan. There are a total of 60 sampling wells. The groundwater samples will be brought to Zamboanga City for Physico-chemical analysis of the following parameters (Total hardness, Calcium, Magnesium, Sodium, Potassium, Sulfate, Nitrate, Chloride, Bicarbonate, and Fluoride). Volatile parameters like pH, EC, and TDS will be measured in the field using a portable EC meter.