Distilled water is a type of purified water that has had both contaminants and minerals removed. Purified water has had chemicals and contaminants removed, but it may still contain minerals.
Purified water is filtered through one of these processes:
- Reverse osmosis filters the water through a special material called a semipermeable membrane. This material allows fluid to go through, but it removes salt and impurities.
- Distillation boils the water, and then condenses the steam back into a liquid to remove impurities and minerals.
- Deionization removes salt and other mineral ions (molecules) from water.
Because distilled water has been stripped of its minerals, it is often used in cars and household appliances. Here are a few common uses:
- steam irons
- watering plants
- car cooling systems
- laboratory experiments
- certain medical devices, such as continuous positive airway pressure devices for sleep apnea