My world is a life-bearing moon orbiting a gas giant. There will be plenty of geysers due to gravitational tectonic activity. Is it possible for geysers to happen in the middle of hot and arid biomes? If yes, could they serve as drinking water?

What I imagined is that hot and salty water is violently expelled and then stays in puddles where bacteria separate the salts and other noxious elements from the water.

With the water being purified in such a way, could it serve as drinkable water and could life forms thrive inside this bacteria-rich pooling water?

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    $\begingroup$ What is drinking it? Native life forms, or unmodified humans? Native life may not be affected by the heavy metals. modified humans may have a means to deal with it. Most bacteria won't purify the water to the extent you're suggesting, although stranger things have happened. $\endgroup$
    – DWKraus
    Apr 17, 2022 at 0:55
  • $\begingroup$ Alien fauna and flora (and the bacteria would neither be akin to earth ones ) $\endgroup$
    – Veknor
    Apr 17, 2022 at 0:57
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    $\begingroup$ Probably worth noting that the water in a geyser comes from groundwater, so I guess you won't really get them in a desert. Maybe it's possible for a geyser to be filled by quite a deep aquifer though, I don't really know. $\endgroup$
    – N. Virgo
    Apr 17, 2022 at 9:03

3 Answers 3


Yes it is possible to have a water supply in the middle of the desert. These are known as artesian wells. Given the right conditions water can flow through permeable strata deep under ground for hundreds of miles, delivering water from mountainous areas where the rain falls to far out into the desert. In some instances where the overlying rocks allow hydrostatic pressure can force the water to the surface.

If volcanic activity were also to be present in a desert it seems entirely reasonable to suppose that that steam pressure could also help expel water from artesian aquifers.



The water is what they've evolved to use:

Since we're talking alien biology, the sky is the limit. If your planet has an atmosphere and there's a food supply (like photosynthetic or in this case maybe even chemosynthetic bacteria), then modest temperatures and water give you a mix for life.

Plenty of terrestrial organisms already live in geysers, so even finicky Terran life can use this water. There are even halophilic eukaryotes like fungi and algae, so salt isn't even an absolute barrier to mare advanced life. While typical Earth life forms won't always do well in such a metallic sludge of radioisotopes and arsenic (mostly extremophiles), these life forms have evolved in these conditions. This is the water evolution has given them, and they would be well evolved to use it. It might be a bit of a stretch for advanced life to have independently evolved in such cramped and limiting environments, but a bacterial soup, with imported organisms resistant to the toxins, or a massive network of interconnected geysers? Sure, why not?

As for geysers in the desert, water can cycle deep in the Earth. Aquifers can supply water for geysers, since by definition geysers are rather deep underground structures. And several moons are known to have subsurface oceans and even geysers associated with them, so a desert is not a hard barrier to geysers in the desert. Geysers from a subsurface ocean wouldn't even necessarily need vulcanism associated with them, but could be driven by simple pressure and might connect up life from multiple areas on the planet.


Where do the salts go?

There is a pool of salty water. Bacteria separate the salts. Where do the salts go? Salts don't get metabolized. They are elements. So the salts are either inside the bacteria because for some reason the bacteria wanted them (they wouldn't), or outside because the bacteria excluded them and just took the pure water up into their own cells (which is what they do in our world).

What remains outside the bacteria is even saltier water because the bacteria are fat and sassy with the good water they sucked up.

I propose that instead you have macroscopic organisms - giant algae or other sessile creatures. These exclude salts and suck up the fresh water. The remaining puddles get super salty and salts even crystallize out.

If you are thirsty, the macroscopic water organisms have the good water inside themselves. You are going to have to eat some of these water-balloon like giant algae, or stick a straw in and drink from it.

Of course you could fiction up some geysers of fresh water if you wanted. I could imagine a hot deep source that was mostly steam on the way up and condensed in the air. Steam has no salts.

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    $\begingroup$ I was going with the assumption of clearing, but good point. Alien life could use precipitated metal oxides like cell walls. Colonial bacteria could even sequester salts in specialized individuals and create deposits in walls around the pools. Still toxic by Earthly standards, but... $\endgroup$
    – DWKraus
    Apr 17, 2022 at 4:10
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    $\begingroup$ Salts are by definition not an element. en.wikipedia.org/wiki/Salt_(chemistry) But you're correct about the salts needing to go somewhere. $\endgroup$
    – sphennings
    Apr 17, 2022 at 6:01

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