Making deionised water at home is a practical way to remove excess ions unique to local water supplies. These ions can include chlorine, copper, and calcium. Although deionised water bought at the store will be free of all ions, those who deionise water at home can choose which ions to eliminate. This means that ions that produce unnatural tastes or are unhealthy can be eliminated while beneficial supplementary ions, such as magnesium or calcium, can be left behind.
Purchase a water filter specifically designed to deionise water. Many commonly available water filters simply purify the water of chemicals such as chlorine and lead but do not filter ions.
Insert ion exchange resin into the water filter. Different ion exchange resins are available for filtering out various ions. Decide on which ion exchange resin to purchase based on local water reports, which indicate the ions of highest concentration in your water supply. Obtain this information by contacting the local water works.
Pour tap water into the filter and wait for it to filter through the ion exchange resin. The water has now been deionised of the ions the ion exchange resin is designed to remove.
Rinse the ion exchange resin with a regenerative solution periodically. This is necessary since an ion exchange resin can only absorb a limited number of ions before it becomes saturated.
Store the deionised water in used soda bottles or milk jugs for later use.
For completely deionised water it may be necessary to use more than one type of ion exchange resin.
Deionised water is free of supplementary minerals and micronutrients that encourage good health, such as calcium and magnesium. Drinking deionised water for an extended period of time may cause malnutrition if other sources of supplementation are not consumed.