Distilled or Purified Drinking water for saltwater tanks

[JCGalaxy02]

Okay so I’m new to the saltwater hobby and I’m looking up the best and cheapest way to get water. I see some with distilled water and then I also have a book about Saltwater Aquariums and it says to use purified water from an RODI system and I’m curious to see if the Great Value purified drinking water was the same? And of course I’d add the salt to but I’m curious about it.
 

It’s also a 45 gallon tank. 

[Chriss Fishes]

Drinking water generally has stuff added to it for taste - bad for aquariums.

 

Distilled is what you need.

[seabass]

As far as buying reef water in a gallon jug, distilled water is the best one to use (as RO/DI water is not sold at Walmart).  Their drinking water is RO water (not RO/DI), which will contain some dissolved solids (and may, or may not be acceptable to use).

 

Distilled water is pure water (which technically should contain zero dissolved solids).  However, when you use a TDS meter to test it, it might read one or two TDS from adsorbed gasses or leached from the plastic jug itself (which is nothing to worry about).

[seabass]

35 minutes ago, HarrisonAquatics said:

Drinking water generally has stuff added to it for taste - bad for aquariums.

It's not always bad.  It's generally elements like calcium, magnesium, and potassium, but could also be salt.  Anyway, you are correct that we can essentially know what's in distilled water.  The contents of RO water, especially RO water with something added, is more of an unknown.

[Chriss Fishes]

4 minutes ago, seabass said:

It's not always bad.  It's generally elements like calcium, magnesium, and potassium, but could also be salt.  Anyway, you are correct that we can essentially know what's in distilled water.  The contents of RO water, especially RO water with something added, is more of an unknown.

Fair enough - I should have been more clear. I was referring to the unknown variables being bad, but I see your point.