Rapid urbanization of the Philippines, especially of Metro Manila area, has caused serious water pollution. Main causes of this are categorized into industrial wastewater and domestic wastewater, discharged without sufficient treatment. As for industrial wastewater, it is essential to put strict regulations on effluent standards, and for municipalities to keep a regular check to ensure these regulations are observed. Philippine government has been working on the improvement of the legislation and control of industrial wastewater until now. However, from now on, it is vital to put more efforts in getting domestic wastewater treated properly. It is indeed crucial to put the existing sewerage construction plans into practice, but generally, sewerage systems require; 1) long construction period, 2) effective funding, 3) high-density construction, and 4) human resources to run the systems effectively. Meanwhile, on-site waste water treatment tanks, or what we called purifiers, can play an important role in controlling the pollution of water environment, and they will serve to complement the sewerage system even after the completion of construction. Small-scale on-site wastewater treatment tanks, or small-scale purifiers, developed and used in Japan especially in developing countries, not only in the scope of environmental conservation but also from the viewpoint of utilizing the economic resources in the private sector

Laguna de Bay is the largest freshwater body in the Philippines with multiple-use. The primary use of the lake is to serve as the future domestic water supply at Metro Manila. The biota of the lake consists of 25 species of fish, 24 species of zooplankton, two species of shrimps, 6 species of mollusks, 42 species of aquatic macrophytes and 154 species of algae. A total of 60 mesophilic anaerobic and facultative anaereobic bacteria and 453 bacterial strains belonging to 22 genera have been identified. A review of 12 papers dealing with biological studies on Laguna de Bay in relation to aquatic pollution is presented. Studies on the impact of heavy metal, pesticide and thermal pollution on the biota of the lake have been sporadic and cursory. There is need for a more comprehensive and systematic monitoring of the lake's pollutants to provide time-series for pollution abatement