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City water is usually not that bad. . .lead is really the only thing that is troublesome, and unless there is a lead pipe somewhere in the system, as opposed to the lead in solder and faucets, all you need to do is let the water run for a few seconds when you first turn it on and the lead will go away.
iron is yucky, but harmless, and will go through your system. It is very hard to remove from tap water.
I do this for a living and have had every water filtration scam there is thrown at me.