Well water

You'ld have to have it checked ( or do it yourself). Most probably yes, but you are going to want to know the ph, amonia ( if any) ect. Most fish shops will check for free if you don't have a kit. I think its recommended to let the water sit for a couple of hours before testing ( right out of the tap may have co2 dissolved in it , which would give an inaccurate reading for ph).
I would think well water would be at least as healthy as "city" water.
 
Yes, definitely get your well water checked first. Never assume that it is "safe" for fish based on looks, smell, etc.

Since you're on well water, the amount of heavy metals could be high, or it could also be high in nitrates (I've heard of 80 ppm off well water before), so it's more the reason to get the water tested.
 
I'll go with the getting it tested folks. Where I live there are large amounts of limestone underground and in fact sometimes, water passes through limestone caves etc. picking up a lot of minerals so the gH and KH can be through the roof for well water down here. Once you know what your home water is tested at, you can decide if you want to mix it half and half with RO or go some other route. Good luck!
 
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