My water system uses chloramine so I collect rain and use reclaimed water from my dehumidifier. Sometimes especially in the winter I have to use RO water I get from Walmart....had an RO unit but it burst during the cold weather..which reminds me to note: don't use an RO unit outside when it's freezing lol.
Outdoors any chlorine/chloramine from tap water or your hose is washed away by rain but of course it doesn't rain indoors. Chlorine can be bubbled off overnight but chloramine cannot be and it will dry out the bodies of soil microbes if not removed. Rainwater is full of microbial life and falls free from the sky when it does; just gotta remember to put out a bucket or get a rain barrel under your gutters to collect it. Not sure because I have yet to try this (scared to...plants are so happy & healthy these daze) but I'd be willing to bet that if you used city tap once or twice to water your plants a flush with rain could reverse some of the damage to microbial populations. But to answer your question yes it does kill off crotters that feed your plants but it's not that hard to find better water sources. In the summer my dh puts off a couple gal a day so I only need to collect rain every so often. Rain is great for making AACTs too plus it contains macros; dehuey water needs calmag as it comes out about 3ppms.