People can’t drink ocean water. However, in very dry areas near the ocean, people purify ocean water. They must use this process to obtain safe drinking water. The main substance that’s dissolved in ocean water is salt, and it must be removed. Salt water is classified as a mixture. This kind of mixture can’t be separated by . Instead, more expensive methods must be used. The first ocean water purification method requires heating. This method, , is based on the fact that water boils at a lower temperature than salt. The second method does not require heating. This method, , has become more common in recent years. Some parts of the world have contaminated water that causes diseases. Contaminated water has microorganisms, and forms a mixture. This kind of mixture can be separated by