Boom

So I had a customer today, who wanted to get some betta fish, and like most customers, was asking after their care and what they needed to buy to ensure the betta fish would do well. 
Specifically the customer wanted to know what type of water they could use.

And like usual I responded with "You can use Tap Water but you need to put a water conditioner in it, otherwise you can use any bottled water or well water, but not distilled water. Distilled is bad." 

Their response? "Or else the fish will explode?" 

To which I was like. O.o Huh?? 
Like....I don't...how? *shakes head* Distilled water won't make your fish explode..... 
It just doesn't have the nutrients within it that the fish need to stay healthy. Hence why it's not usually recommended for tanks. 

-Sarnic Dirchi