View the original post on Musing.io
It is said that water is not uncommon in the universe. The idea that lead to other plants not having water is that they could not hold it for long as it is striped away.
Water came to earth from the outside, as Earth could have been had water when it formed due to the extreme heat that would turn the water to water vapor and blast them away. Moreover the water could not have been made in Earth. Thus the only logical solution is that water came from area further away from the sun that water could have existed in ice form.
That leads to the conclusion that water may have came through comets, they are pieces of rock, dust and ice after all. Nevertheless that is not the case as they have a higher concentration of heavy water (water that is formed from a hydrogen isotope (isotope being that atoms that have the same number of protons but different number of neutrons), deuterium, which is heavier than normal water as each hydrogen has an extra neutron.
Note: excess heavy water in your body is poisonous as it slows down metabolic process (source: cody's lab).
This leaves meteoroids mainly carbonaceous chondrite, which are meteoroids rich in carbon and water that has the same chemical composition as our Earth's water.
The main source of information for that answer is from minute earth
