AV took a different approach, at least for baths. Rather than filtering, he'd add things that would bind with the toxins and prevent them from entering your body through your skin/lungs, as well as pull toxins from your skin. He recommended using a little terramin clay and sometimes a little milk.
Most filtering would probably improve your water quality, assuming your water quality is bad (tap water). If you have decent water, some filtering methods could even add toxins.
For example, most shower-head filters designed to remove chlorine while keeping a good flow are made of heavy metals. Yes, you'll get rid of the chlorine and some other toxins, but you could be adding something even worse.
As I understand it, carbon filters restrict flow too much to be convenient for a shower-head installation.
Some of what I've read suggests that filtering should be done centrally rather than at the shower-head if you want it to be effective and safe. But of course that is more expensive, and you can't take it with you when you travel.
