I have had Goodluck using chloromine water. I dont remember where i heard of it but the process I use to get it out is to aerate and circulate the water, and add a little tiny bit of molasses. You cannot off gas chloromine directly, I think the molasses converts it into chlorine or something which is then offgassed. After 6-12 hours you can smell a difference and your microbes will grow.
In a weird coincidence, a man from the New Orleans Sewerage and Water Board just came by my work to test the water. I asked him about the chloramine and he said its extra high right now because of a Brain Eating Amoeba outbreak recently. Makes you really think about what your putting on your garden.
I found a seemingly good article about removing the stuff. It is geared for brewing beer, but has good examples about how long it takes to reduce it to a level where microbes will thrive. Removing Chloramines from water I personally don't drink it, but many fear an amoeba or microbe that can kill them so they rather have a little chemical in their drinking water. I have heard a few people around here even say they preferred using chloramine water with their animals because it was safer. I think my chickens generally let it sit long enough that it loses the scent.
Rainwater is preferable, but having chloramine water does not have to stop you from getting started brewing.
It is pretty easy to build your own carbon filters, I use a section of 2" CPVC pipe, fittings to hook up garden hoses, fine mesh screen and crushed, home made charcoal. I also have a layer of fine sand in mine which is separated from the charcoal by two more pieces of screen. It is 4 feet long and works very well, easy to remove the old stuffing and put in new stuffing makes it even better.
Right on Stephen I'll tell you since finally trying out some tea it's become a staple regiment for my garden!! Below is some information I always find very useful come every spring -this guy knows his stuff!! He offers products as well if you're interested but the data he provides is excellent, thorough and free it is all well worth the reading I assure you.