I have a ac unit that has the amazing ability to create what is essentially reverse osmosis water (its drained as waste) w00t. Its a perfect piece of equipment the waste water from cooling the inside/removing humidity from the room creates almost the perfect amount of water to get everything done. And when you check the ppm its runs around 28 instead of the 190 straight tap here runs. Although I run a brita and let it sit and get the ppm down to 140 in 24 hrs and mix that in my rez and the result is water with ppm around 60-110.