I’m going to go out on a limb here, but if we manage to get astronauts to another planet they will have a water filter with them. 
So, yes…it would be safe to drink the water, since it would just be water.
Here in Minnesota, we are well acquainted with the concept of non-liquid water. Even in April, we still have piles of it at various locations.
Theoretical plans for colonizing the moon, Mars, etc. often include capturing ice comets as a source of water for terra-forming the area. (Turns out the problem is keeping the liquid water there, in low gravity.) But presumably there would be filtering plants before drinking the water. After all, we do that with the water here on Earth, too.
I know all the forms of water, but when the subject is drinking water, does it really need to be preceded by the word “liquid”?
Assuming that you have an essentially unlimited supply of (solar) energy, separating and purifying water is straightforward. Although the particular techniques have not been developed or proven out, evaporation and distillation can produce virtually pure water.
Stranger
You don’t put ice in your drinks? What are you, some Englishman who drinks warm beer? 
And don’t say that they don’t drink it until it’s melted. I once worked next to an annoying co-worker who crunched ice all day long.
Also, dehydrated water comes in powder form.
That is brilliant! You just add water and you have real, clean, cold water! Someone should market this!
Tritiated water (i.e., water with tritium, or [sup]3[/sup]H) is radioactive, and would take much less to cause problems for humans.
The only stable isotopes of Oxygen are O-16, -17, and -18. All of theses could presumably be found at significant concentrations on a planet depending on the planet’s sun. But I can’t find anything about the toxicity of water with O-17 or O-18.
It’s currently selling for $10 per can on Amazon. That’s pretty good marketing, IMHO.
There may be cases where, due to temperature and pressure, the water is liquid on the planet but freezes or boils when brought inside the human-friendly living space (let alone when put inside a human).
For instance, because of the atmospheric pressure of the planet, the water is liquid but it’s also 300 degrees C, so it’d immediately boil (or explode) when brought inside where the pressure is more Earth-like.
Absolutely. And a bargain at double the price! I’m going to order a case of it, in the event of a power failure or the end of the world I’ll always have water I can mix up with just some water! I’m set!
I’m going to sell my own with a little salt at the bottom and call it dehydrated mineral water…
Agree; however water can form Azeotropes, which can be broken but it is non-trivial. The most popular Azeotrope is water-ethanol which normal distillation is not able to break. Here are a list of other water Azeotropes : Azeotrope tables - Wikipedia
There is also the possibility that water comes with something very corrosive like Hydrogen-fluoride or nitric acid which will be a nightmare to separate in space (it could be done but it’s not trivial).
Also I know some planets have ammonia and raises the possibility of having hydrazine too. So if you an explosive compound like hydrazine, distillation again will be non trivial.
The liquid water that exists in our solar system is nearly all salty, so would be undrinkable without treatment. Europa is covered in brown discolouration that seems to come from salt deposits on the surface, probably sodium chloride but there may be other materials there as well.
Maybe the ice in a comet would be more pure, but that seems unlikely, since many comets are coated with a tar-like carbonaceous residue. Mars water will probably be contaminated with some nasty stuff, like calcium and magnesium perchlorate. So the outlook for fresh water in the Solar System looks grim.
The largest reservoirs of water in the system may be inside Uranus and Neptune; current theories include a mantle of high-pressure ice inside each giant, mostly water but also including ammonia and methane ices. These reservoirs of material are very inaccessible, and would be in a particularly dangerous state in situ - if you could teleport the ice straight out of Neptune’s ice mantle, it would be at such a high temperature and pressure that it would immediately boil explosively.
If I could cabbage a related question onto this one:
Is it possible to produce chemically pure H2O (as in, no adulterants of any kind) in a laboratory? Is it safe to drink? Is this “distilled” or “purified” or “whatever” water you buy at the grocery store chemically pure H2O?
There are differing grades of purity as designated by standards established by the American Society for Testing and Materials (ASTM), Clinical and Laboratory Standards Institute (CLSI), the American Chemical Society (ACS), US Pharmacopeia (USP), the International Standards Organization (ISO), and others. The required standard and means to achieve it depend on the particular application. The stuff you purchase in thr grocery store as distilled water is basically the poorest grade of purified water (not counting filtered bottled drinking water that is advertized as “purified” even though it meets no particular standard) and is contaminated just by virtue of being stored in high density polyethylene jugs.
Chemically pure H[SUB]2[/SUB]O poses no health risks beyond that it will tend to more aggressively bond and remove alkali salts simply because it isn’t carrying any. You’d have to drink a considerable amount of water without replacing those compounds from food for this to become an issue.
Stranger
This? Oh, it’s just water from BD+49 828 b – you wouldn’t have heard of it.
Ever do any Winter camping or survival training? One gathers a solid form of water and then melts it to liquid for drinking water. My guess is that you would object to the terms “drinking snow” and “potable snow” too, though.
Solid water= ice (many types of water Ice, also) You have likely consumed solid water.
Gaseous water= steam.