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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?

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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 '15 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 '15 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. $\endgroup$ – Andrew Thompson Sep 29 '15 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 $\endgroup$ – James Jenkins Sep 29 '15 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 '15 at 14:35
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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.

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  • $\begingroup$ 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. $\endgroup$ – b and d restore Monica Jan 27 at 21:04
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Mars lacks just about everything else for creating sustainable life. The most damning -- and the one that everyone seems to forget -- Mars has no magnetosphere or atmosphere like we do. The solar wind is not at all deflected around Mars and gamma radiation destroys DNA. It is just too small to have either -- not enough mass to hold onto an atmosphere gravitationally and it apparently also does not have a sufficient core to create a magnetosphere.

The water would not only be unsuitable for life as we know it -- it would also be irradiated to toxic levels. On the upside, however -- it should be relatively virus free.

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    $\begingroup$ Water itself does not undergo any particular change when you irradiate it. Water with radioactive particles suspended is a health hazard, but otherwise there's no real effect. $\endgroup$ – Nathan Tuggy Sep 29 '15 at 17:04
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    $\begingroup$ I don't know that I'd make that "Virus free" claim. I don't know how the per square meter radiation dose stacks up between the main reactor of chernobyl and the surface of mars, but Radiotrophic fungus have been found living in Chernobyl. No reason to believe if life did exist on mars that it couldn't adapt to the extra radiation (still, this ignores the lack of significant atmosphere) $\endgroup$ – Sidney Sep 29 '15 at 18:14
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    $\begingroup$ In very broad terms the only form of radiation that can cause objects to become "irradiated" is neutron radiation, which is unaffected by a magnetosphere. Even if you were to "irradiate" water with neutron radiation. It is pretty harmless. Tritium has such a low energy beta its safe and unstable Oxygen isotopes are so unstable that they could only pose a threat if you were exposing yourself to the neutron source (in which case you are actually dead, you just don't know it yet). $\endgroup$ – Aron Sep 30 '15 at 10:27
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    $\begingroup$ Mars is plenty massive enough to have an atmosphere. It even supports weather. Though it is quite different from Earth's, being about 100 times thinner and 95% CO2. $\endgroup$ – 8bittree Sep 30 '15 at 13:57
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    $\begingroup$ @jinzai Almost everything in your last comment is both false and easily checked: most kinds of radiation (including gamma rays and charged particles) have no effect on water at all (exceot to warm it up briefly). Martian soil is also not very radioactive -- it wouldn't do DNA much good for various chemical reasons, but not due to radiation. Mars can hold some gasses (heavier ones) and while they do get blown away, it takes a while. Gamma radiation is not charged and is not part of the solar wind. $\endgroup$ – Steve Linton Jan 27 at 17:46

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