Distilled water can be rather expensive, if you choose that route, as well as having a lot of plastic bottles. Another alternative is to use an RO (reverse osmosis) water filter system under your sink. I believe you can purchase a system for around $150.00, which in the long haul will save you money. This also removes the chlorine and chloramine that may be added to municipal water systems. You can also use the RO for misting.
There have been questions about the distilled water possibly causing problems with even terrestrial frogs that occasionally like to splash around in it, because it may cause an electrolyte imbalance due to osmosis over the frogs' permeable skin membranes. However, unless it is in a totally isolated system, the water will again pick up some minerals from your substrate and gravel to alleviate this problem. It does need to be re-mineralized for use with tadpoles, but this doesn't take much--a little substrate, floating moss such as Java, and/or Black water extract will do the job.
While I use distilled water for misting, I still use my well water, which is very hard due to calcium carbonate compounds and does leave heavy deposits, for the ponds and waterways. I clean up the deposits by wiping the glass with paper towels dampened with straight white vinegar, a chore that must be done regularly, anyway. If you're on a municipal system that adds chloramines, which don't dissipate with ageing as chlorine does, you should use an aquarium water conditioner to the tap water.
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Patty
Pahsimeroi, Idaho
D. auratus blue
D. galactonotus pumpkin orange splash back
D. imitator
D. leucomelas
D. pumilio Bastimentos
D. fantasticus
P. terribilis mint and organe
D. reticulatus
D. castaneoticus
D. azureus
P vittatus
P. lugubris