A new study carried out by scientists from Stockholm University in Sweden suggests that water actually exists in two different forms having major differences in terms of structure and density.

In the new research, scientists used X-rays to study H2O molecule in unprecedented detail, and reached the conclusion that water is “not a complicated liquid, but two simple liquids with a complicated relationship.”

“The new results give very strong support to a picture where water at room temperature can’t decide in which of the two forms it should be, high or low density, which results in local fluctuations between the two” said one of the researchers, Lars G.M. Pettersson.

Water is essential for life on Earth. It is one of the most fundamental molecules. According to scientists, about 70 properties of liquid water are unique from all other liquid substances. For years, scientists have believed that water exists in three distinct phases: solid (ice), liquid (water) and gas (water vapors). It has second-highest surface tension among all liquids (Mercury has the highest surface tension among liquids). Water expands when it freezes (unlike almost every other known substance). Water molecule has a large boiling point—compared to other hydrides—for such a small molecular weight.

Researchers used two different types of X-ray imaging devices to find out how distance between H2O molecules changes as water changes from an glassy, amorphous, frozen liquid state to a viscous liquid state to another more viscous liquid state with lower density.

X-rays devices at Argonne National Laboratory near Chicago demonstrated two different structures of water. Then the large X-ray laboratory DESY in Hamburg showed that the two phases indeed both were liquid phases. Researchers found that water can exist as two different liquids at low temperatures where ice crystallisation is slow.

“The new remarkable property is that we find that water can exist as two different liquids at low temperatures where ice crystallization is slow”, says Anders Nilsson, professor in Chemical Physics at Stockholm University.

Last year, researchers from Oxford University had also suggested in their study that liquid water could ‘switch’ states between 104 and 140 degrees Fahrenheit, and demonstrate completely new properties.

The latest findings will now verified by other independent teams of researchers before reaching the final conclusion.

The detailed findings of the study have been published in the Proceedings of the National Academy of Sciences.