best shower filter/ body powder?

shower filter, of course, because i want to get out all that harmful stuff. as much as i can!
in the mean time, is there something i can put in my bathtub water to eleviate some of the toxicity? probably wishful thinking,...but you never know...

and well, i have bangs. my bangs tend to get oily when i sweat and work out. some of the pieces arent exactly long enough to just pin back and usually i just put some baby powder on a brush and brush it through to absorb the powder but suddenly im remembering talc may be bad for you...granted the amount i use is small...if there is a safer type of powder i'd love to know.
please? i'll kiss your feet for your seeeecrets