Distilled water is water that has virtually all of its impurities removed through distillation. Distillation involves boiling the water and then condensing the steam into a clean container, leaving most if not all solid contaminants behind. Drinking distilled water is quite common. Many beverage manufacturers use distilled water to ensure a drink's purity and taste. Bottled distilled water is sold as well, and can usually be found in supermarkets. Water purification, such as distillation, is especially important in regions where water resources or tap water is not suitable for ingesting without boiling or chemical treatment. Water filtration devices are common in many households. Most of these devices do not distill water, though there continues to be an increase in consumer-oriented water distillers and reverse osmosis machines being sold and used. Municipal water supplies often add or have trace impurities at levels which are regulated to be safe for consumption. Much of these additional impurities, such as volatile organic compounds, fluoride, and an estimated 75,000+ other chemical compounds are not removed through conventional filtration; however, distillation does eliminate nearly all of these impurities. Distilled water is also used as drinking water in arid seaside areas which do not have sufficient freshwater, by distilling seawater. It is quite common on ships, especially nuclear powered ships, which require a large supply of distilled water as coolant. The drinking water is produced in desalination plants, needed to boil water. Alternative technologies like reverse osmosis are becoming increasingly important in this regard due to their greatly reduced costs.