In water and waste treatment, cationic polyelectrolytes can function as either primary coagulant or coagulant aid because they are positively charged. It has been known that most of the colloidal and suspended impurities in natural water have negative surface charges. Cationic polyelectrolyte will neutralize the impurities or pollutants, then agglomerate them into larger masses for rapid solid-water separation by sedimentation, flotation, centrifugation, filtration, or reverse osmosis. Anionic polyelectrolyte are negatively charged and function as coagulants in water and waste treatment. They must be applied along with positively charged coagulants which neutralizes the negative charge on the colloidal and suspended impurities. In a water softening process, where precipitation particles are positively charged, however, anionic polyelectrolytes alone can coagulate. Nonionic organic polymers, however, can only function as coagulant aids which should be introduced at a point shortly after flocculation first occurs. Nonionic polymers will coat the existing floc particles so that when the flocs collide, they will adhere to one another, thus forming larger and heavier masses. This paper initially describes the various applications of organic polymers in the fields of environmental, chemical and biomedical engineering. Subsequently a new technique for the accurate, quantitative determination of polyelectrolytes in the 0.00002 N to 0.005 N concentration range is introduced. The principles, apparatus, reagents, and analytical procedures of the method are presented in detail. The test procedure developed can also measure the net charges of colloidal substances, this can be used for chemical coagulation process control.