There was a time when it was thought that heating distilled water was dangerous because it heated faster than regular tap water. It has since been proven wrong. Distilled water does not heat faster than running tap water.
The definition of distilled water is water from which all impurities have been virtually removed by the act of desolation. Water is distilled by boiling it. When the water boils, the steam is captured and then recondensed in a clean container.
Many companies have started looking at less expensive alternatives to purifying water, one such method being water deionization. So far, alternative methods, although effective, have not been able to completely purify water.
Distilled water is commonly used in automotive cooling systems, steam irons, and lead acid batteries.
Another popular use for distilled water is in aquariums. Aquarists use distilled water in their aquariums because it does not contain the chemicals often found in running tap water. Many tap waters contain chlorine and chloramine, which are deadly to fish.
Too often aquarium owners are stunned to learn how much money they spend each year just buying gallons and gallons of distilled water. One way for saltwater aquarium owners to save money is to distill their own water, provided they are willing to improvise. The first thing to do is find a place to heat/boil the water, which can be done with a gas or electric stove. Any normal pan will do for heating.
Then you have to find a way to collect and cool the vapor because the typical cooler is made of a long copper tube in the shape of a spiral. Owners of saltwater aquariums will have to find another piece of tubing because copper-distilled water is fatal to invertebrates that live in coral reefs. If you can't find a spiral hose, consider using a saucepan and its lids. When the water boils, it begins to condense on the lid of the pan, it is distilled water.
Cover the pan with the second lid and pour the condensed water into a cup. Repeat the operation until you get enough water for your tank. It takes a long time to collect enough water.
When setting up a saltwater aquarium, it is important to remember that distilled water must be supplemented. By itself, distilled water is too pure to support aquatic life. It is also important to ensure that the distilled water you use has not been stored in containers containing copper. Adding copper to salt water is deadly to invertebrates that live in coral reefs.
Anyone who is unsure of the purity of their tap water should plan to use distilled water when setting up a saltwater aquarium. Be sure to add a mixture of salt water to distilled water.
After filling the tank with water and installing your filtration system, it is recommended that you leave your tank empty for a few days. When the water quality is okay after the tank has been running, you can add your fish. Double-checking your water can save you from accidentally destroying your fish.