I would like to know how similar Mars water is to Earth water. Can we survive on Mars with Martian water without any major health issues etc?

  • $\begingroup$ There has been an edit suggested: "how long would we survive on mars with the water?" This changes the question, does not fit with the existing answers, and ought to be asked as a separate question. $\endgroup$
    – DrSheldon
    Apr 28, 2021 at 4:57

2 Answers 2


Fundamentally, water is water. In its purest form, it is the same anywhere, except perhaps for the isotopes. However, one of the wonderful things about water is the fact that it's a good solvent, and in fact has many things in it that aren't water. For instance, one could not survive off of ocean water: we humans require fresh water.

The one potential difference is in the isotope of the water. This is a rather complex concept, basically some water is heavier than other water, despite having the same chemistry. It turns out that Mars has a higher concentration of heavy water than Earth does. However, it is still within reason to us humans to use. It would make fusion easier, but that's another matter entirely.

The water that was discovered on Mars recently is unique. It is believed to be a very salty water; in its natural form humans could not drink it. However, it can go through a desalinization process, where the salt is removed, and in theory it should be drinkable. Basically, the water needs to evaporate, then re-cool.

As was said in the press conference, the best source of water for astronauts would be in the ice caps, which are similar to Earth's ice caps: frozen water on the surface, which would simply require melting to use, along with a small purification process.

Bottom line, there is water on Mars, and through some purification process, it can be made for human consumption.

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    $\begingroup$ There isn't much life in the dead sea, and Mars water is much saltier $\endgroup$
    – PearsonArtPhoto
    Sep 29, 2015 at 11:31
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    $\begingroup$ That kind of water's probably okay, I just wouldn't want any Tritiated water. Still, I'm sure the isotopes are similar to that of Earth's, but I'll look into it. $\endgroup$
    – PearsonArtPhoto
    Sep 29, 2015 at 14:05
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    $\begingroup$ @TildalWave "I wouldn't really drink highly deuterated water" Why not? It is not radioactive, and despite being slightly more dense, it should have the same chemical properties as non-deuterium based water. $\endgroup$ Sep 29, 2015 at 14:06
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    $\begingroup$ Earths ocean water can also go through a desalinization process to be drinkable. Currently 1% of the Earths people are dependent on manual/human desalinization for survival (per wikipedia) ultimately the other 99% of Earth people are dependent on naturally desalinated water for survival $\endgroup$ Sep 29, 2015 at 14:22
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    $\begingroup$ @AndrewThompson See Heavy water#Effect on biological systems, including toxicity: Mammals, such as rats, given heavy water to drink die after a week, at a time when their body water approaches about 50% deuteration. Hydrogen bonds work differently. $\endgroup$
    – gerrit
    Sep 29, 2015 at 14:35

This discussion on quora talks about deuterium abundance on Mars:

Deuterium occurs naturally on Earth in water as 1 in 6,400 hydrogen atoms or 1 part in 3,200 by weight. On Mars it is one deuterium for every 1,284 hydrogens.

So high enough to be noticeable in a lab (for example Mars water is about 700 ppm denser than Earth water under equivalent conditions) but not enough to be relevant for drinking.

  • $\begingroup$ This is an important point, thanks for the numerical value. It would be good to have some sense of human toxicity. Wiki suggests 25% deuterium is toxic, but no safe level stated. Humans on Earth said to have 1.1g D, equivalent to 5.5g heavy water; Mars would give 4.4g D, equivalent to 22g heavy water. $\endgroup$
    – Bit Chaser
    Jan 27, 2019 at 21:04

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