The boiling point of pure water is 212 degrees Fahrenheit at one atmosphere of pressure, or 760 millimeters of mercury. Such conditions are known as standard pressure. The boiling point is affected, however, when the pressure rises or falls, according to the Department of Chemistry at Purdue University.
The relationship between pressure and boiling point is direct. When the pressure is lower than one atmosphere, the boiling point is also lower. When the pressure is higher than standard pressure, the boiling point increases. For this reason, pure water boils at slightly different temperatures depending on altitude. The boiling point is the temperature at which a liquid, such as water, changes into a gas.