This study aimed to determine the solid waste disposal practices among informal settlements in Barangay Malabanias and to determine the water quality of the Abacan River and its implication for human health and the environment. A cross-sectional survey was distributed among the 155 randomly selected participants of the study. 5-Day BOD Test, Azide Modification Test, Stannous Chloride, Phenate, Colorimetric Brucine, Argentometric, Visual Comparison, Gravimetric method, and Multiple Tube Fermentation were done to water samples for BOD, DO, Phosphate, Ammonia, Nitrate, Chloride, Color, TSS, and Fecal coliform, respectively. Parameters with extremely low stability such as Temperature, pH, Conductivity, and TDS were measured on-site using handheld meters. Water quality parameters of the Abacan River, such as Stream flow, temperature, TDS, Conductivity, Phosphate, BOD, Fecal coliforms, conductivity, and DO in all sites gave values not conforming with the permissible level which may pose danger two human health and aquatic environment. Correlation gave the value of r=0.997 and p= 0.048 between the pH and BOD. As the water pH increases, the BOD of water also increases. Furthermore, TDS and Conductivity gave values of r=0.999 and p=0.026, which implies that as the total dissolved solids increase, the Electric Conductivity of water also increases. Solid waste disposal practices of informal settlements are anchored with poor solid waste management and may only be one of the possible sources of potential contaminants on the Abacan River; thus, important attention should be given to the water quality of the Abacan River to prevent further degradation and contamination of other water bodies.