Hello,
Yes it is recommended that you use distilled water in your reptifogger, and in misting the enclosure but not spring directly or in the water feature or bowl of your
terrarium.

The reason it is recommended in the fogger is that over time the minerals in filtered/bottled/tap water will build up in the fogger and shorten its life.
also distilled water is recommend for misting the enclosure so it will not leave mineral deposits on the glass and ornaments.

You can buy distilled water in just about any super store or grocery store by the gallon.

To tell you the truth the inexpensive bottled water that does not say that it has minerals added will be just fine.
I have been running target brand bottled water in my foggers for almost 2 years and no problems. but I do
clean my forgers out in the sink (with out getting water in the electronics base) once a month to so.

The only thing I've had to do is replace a fan, witch is pretty easy.

As long as you have them on a level surface the fan will last a long time and will last even longer if you use a controller of some type.

I like the zoo med HT-10 hygrotherm.
you can get them pretty cheap on amazon for about $40.00 plus shipping.