A water ionizer separates water into an alkaline fraction and an acid fraction. It does this by exploiting the electric charge of the calcium and magnesiumions present in nearly all sources of drinking water. When a source of water lacks mineral ions -- such as distilled water or water filtered via reverse osmosis -- a water ionizer has negligible effect.
Testing
The pH of the water can be determined using a test kit test; many ionizers include a pH testing feature, as well as a meter to assess alkaline water's reduction potential.
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