This thread seems to be suggesting carbon filtered is best. The higher ppm and better taste of the fridge water is probably a carbon filter, maybe with some mineral additive (an Ro filtered fridge would be pro
). What's in the bitch?
Chlorine seems to be the issue with mineral content undecided.
RO is the best, but it certainly isnt necessary for an amazing product. RO provides you with 99.9% clean water, meaning after you add whatever you add you know exactly whats in your solution. but this also means the minerals present in tap and well water are missing and sometimes must be replaced with CalMag or other supplements
i have no experience with using fridge water because when i compared it to my straight tap it was about 10-20ppm higher. between the minimal difference and the slow dispensing of the fridge filter i just went with 24 hour tap.
using 24 hr tap or well with ppm's as high as 400 more often than not will present any problems whatsoever. 500 ppm is the set limit for drinkable water in the US, if you can drink it so can your plants.
simply fill your container(i use milk jugs) the day before you need it. the chlorine will outgas in 24 hours and its perfectly good for your plants. i use it straight from the tap when dealing with clones, the chlorine helps keep everything sterile.