Magnetic field measurement and intensity of light emitted have been done through water medium. Measurement of light intensity is done by lux meter by assisted by irradiation from flashlight to know light intensity. The problems of water sources include the quantity and quality of water that are unable to meet the increasing human needs and especially for consumption. In this research method can be done by giving coil that serves as conductor of electric field generated by magnet. Pollution present in water, can be precipitated by dissolved ion dissociation. Magnetic fields can accelerate the decline of water hardness. If the level of water hardness decreases, the intensity of the light produced will be greater.

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