best way to get RO water?

You can buy a machine that cleans your tap water but that comes with headaches down the road. Or you can find a Walmart or someplace that sells 5 gallon water cooler jugs of RO. RO isn’t what it’s all cracked up to be. Be careful, do not try to stick your PH pen in straight RO. There’s nothing in the water and your PH meter will aimlessly drift. It can also damage your meter. So if you’ve stuck your meter in straight RO it’s probably best to recalibrate and not try to measure PH in straight RO water. Once you put nutrients in the water that’s fine to test and adjust PH. Honestly when I was a new grower I was all about the RO until I realized it was more work than it was worth. My tap water comes out at 59-62 PPM so I just use that once I bleed off the chlorine by letting it sit. I would test your tap water and if it’s suitable just use that. Unless your community uses Chloramine to treat the water, in that case Chloramine doesn’t bleed out of water like chlorine does. If your tap water is a bit high in PPM you can always try to filter it with a Brita filter to clean up a bit. You’d be surprised how much a Brita filter reduces the PPM.