Natasha Vitez explains why shower filters fail: hot water deactivates the activated charcoal, destroying its ability to remove chloramine, chlorine, and metals. Filtration has to happen before the water heats up to actually work.
Shower filters are mostly B.S. and here's why. Activated charcoal gets deactivated by heat. So if you're putting hot water through a charcoal shower filter, it's not going to last very long at all. And you really want to get the chloramine and the chlorine out of the water, not to mention all the metals and stuff. So you kind of need to filter the water before it goes into the hot water heater where you can get it when it's cold. So there you go.
