Our municipal water is treated with free chlorine so a charcoal canister filter (mounted outdoors near where I brew) strips it out easily. I also use a portable R.O. system to make water which I use to dilute my filtered tap water for brewing, diluted more or less depending on the beer I'm making. I was doing the supermarket RO water routine for a while, but frankly I ain't getting any younger and this is a heavy enough hobby without having to tote buckets or carboys full of water in and out of the car and up and down stairs. So over-paying for the portable HbrewO RO system was worth it to me purely for the convenience and portability of the system. Their replacement cartridges are relatively small, and proprietary, and not inexpensive. But it works great for me, my beer, and my fish.
When I make a batch of R.O. water it's usually 20-30 gallons at a time whether I'm planning a brew or not. We also use it for replenishing our aquariums in between water changes (the fish seem to like that routine), and about a 50/50 dilution for our coffee maker reservoir to help with mineral deposits. Lowe's or Home Depot sell a handy $12 hand pump (Primo brand) which fits any plastic carboy. We keep a 3 gallon Better Bottle tucked in a corner of our pantry with that pump on it for coffee maker refills.
And yeah, get your water tested, and get Martin's Bru'n Water spreadsheet. Even if all you do is dilute your tap water with RO or distilled water like I do, the spreadsheet will tell you your results with any dilution ratio you choose, once you create a profile for your own tap water.
Sent from my HP Slate 10 HD using Tapatalk