I read a post someplace about someone doing larger grows, which makes water cost more. He filled up a large container with tap water and let it sit for a week to off-gas the chlorine, then used it for plants.
Where I live the tap water also has arsenic in it. No tap water for my girls! I use RO water which means I no longer need to buy and transport water, I need it to drink and cook with.
I have posted on the topic more than once about chlorine and chloramine.
Your are 100% correct that you can gas off chlorine the best way to achieve this is to put an air stone in a bucket of water in a dark place and let it bubble for 24 hours the bubbling affect will release the chlorine faster.
Now chloramine doesnāt gas off like chlorine. You need to call your water company and request whatās product in your water. They have to provide you with this information at least in Canada they do. They will even provide lab reports on the make up of the water.
Since my water supply consist of chlorine I havenāt done a lot of research on chloramine but I did read a article before that says you can put the drops in for fishtanks and it will remove it but youād have to do your own research to confirm this
Before my Ro system I always Bubbled my water
This why I quit posting so much. I found ALL my information searching this site. I took what I wanted and left the rest. @Todd.grobo and @FireGuy @Mpower11 weāre my influences. Grateful for their posts. 
@Gunk No, you canāt kill Arsenic, itās a naturally occurring mineral. Just bad for us to ingest. I bought an RO system and Iām using that for my grow, humidifier and for drinking water. Where I live, itās not safe to drink the water. No more lugging 5 gallon bottles from the store!
Was the best setup for me.
When I was running Ro water in humidifiers that have wicks. I donāt know the reason why but after a couple weeks it stop working properly. After I changed my water source back to tapwater problem was solved.
So if you run into a problem where itās not producing humidity like it used to possibly need to change your water source.
I know this sounds crazy but that is what happened to me
Thanks! Iām using an ultrasonic, so no issues.
There are simple countertop water filters on Amazon that remove arsenic, chlorine and 97-99% of a lot of other things. This is a cheap one I am looking at.
The Aquagear Water Filter Pitcher removes up to 99.8% of arsenic, up to 99.9% of lead and chloramine, and up to 97.8% of mercury.
The water filter pitcher can also remove fluoride, chlorine, mercury, and at least 50 volatile organic compounds.
I sent almost that exact RO back, no joke, took 10 minutes to fill a drinking glass. This one I sent back the same day, would take me days to fill 1 Grobo it is so slow.
How fast it fills is a function of your water pressure, mine is on the low side and it takes about 3 hours to fill a 5 gallon bottle. I fill two per week so it meets my needs quite well. They do offer an inline booster pump for folks who need a faster flow. I was using bottled water now with RO Iām not using any PH up/down.
One thing I learned about buying a RO system is make sure you buy a brand that you can easily buy replacement filters forā¦ Alot of these systems on Amazon are here today and gone tomorrowā¦ Then you end up with a Ro system that you canāt find filters forā¦ For this reason I would stay with a name brand product that will be easy to buy filtersā¦
A second option vs getting a booster pump is getting a pressure tankā¦ Both options work good
Here is a explain of a pressure tankā¦ I use this tank to automatically fill my humidifier in my tent
