Drainage capacity refers to the ability of teh soil to absorb rainfall and other forms of precipitation. For the town of Alaminos, drainage capacity is almost uniform due to the fact that soil type and geologic rock formation are not very differentiated. The remaining factor that affects water absorption or infiltration is the slope. The higher the slope percentage, the lower is the infiltration rate.

    With regards to Alaminos' drainage system, there are three (3) river networks that naturally drain all surface run-off waters. Kaquinkong River and Onipa River collect about 80 percent of the total run-off. These rivers drain towards Quezon Province through the Matanag River of San Pablo. Only 20 percent of surface run-off drains to Laguna de Bay through the Tigas River.

    The head waters of Onipa river is being tapped for potable water and the downstream can be used for recreational purposes.