I've always used bottled water to spray my mantid's enclosures. This was fine when they were in cups, but since moving them to larger terrariums and now with the springtails and needing the soil to be so moist, I was wondering if bottled water is necessary. I'm not sure if tap water is safe for the mantids and springtails due to the chlorine?
Honestly few use anything besides tap water.
The real advantage to using "spring" and other filtered water (such as RO) is to prevent hard water spotting the habitats walls from tap water - which looks bad and makes photographing even more so.
For chlorine you can do the old aquarium keepers trick of filling a jug with tap water and letting it set overnight without the cap, so the chlorine can dissipate (can take 48 hours). The larger surface area exposed to air like in a bucket the faster it can dissipate, but is not as convenient and can lead to issues such as hair, dust, etc settling on the water surface.
In recent years though chlorine has been replaced with chloramine in many water treatment facilities, you will have to ask to know; however,
chloramine can only be removed by filtering. Fluoride is another additive that can only be removed by filtering as well.
Personally I found my springtails and isopods do better with tap water, which I can only assume is from the tiny amounts of minerals in the water that is removed by filtering. My mantids have been unaffected by tap or distilled water however.
Recently when I added in my water humidification system, and water refill station, I added a simple
activated carbon filter system (
filters) inline with it's own water supply line. That removes the chlorine/chloramine/fluoride/heavy metals/odor/etc from the tap water, without overly purifying it for my plants and pets. In that regard you can use the simple Brita style
water pitchers (or
faucet adapter) to do the job of basic carbon filtering too.
The adages such as, "an ounce of prevention is worth a pound of cure", or "better safe than sorry" apply here for most. Use/filter water if you do not want to worry, or prefer the non-spotted habitat walls, otherwise it doesn't seem to be a issue.
