The skin is the bodies largest organ and it absorbs whatever is in your water. I think this is an often made but incorrect statement.
How many times have you read that skin absorbs 60% of whatever is applied to it? Yet there is no evidence to support this figure. In practise, the skin will absorb anything from 0% to 100% of whatever contacts it but in general the primary function of the skin is to act as a barrier that prevents the intrusion of external materials. Cosmetic companies actually have to work hard to develop formulations that can be absorbed into the skin to deliver all the benefits the consumer expects. - http://www.thefactsabout.co.uk/content.asp?menuid=32&submenuid=117&pageid=117&menuname=How+do+moisturisers+work%3F&menu=sub
Also see: http://skeptics.stackexchange.com/questions/5415/are-minerals-chemicals-absorbed-through-your-skin-during-bathing
http://www.survivalistboards.com/showpost.php?p=5052498&postcount=27
http://www.newton.dep.anl.gov/askasci/gen06/gen06003.htm
I'm gonna have to go with my initial statement...
Is the skin the largest human organ?
Now I will agree that there are a number of factors that come into play when accounting for absorption and permerability of the skin. And yes, cosmetics, as well as topical ointments, salves and such do require a carrier that assists in penetration of the top layers. This is also a factor in where the item is to penetrate, i.e., topical delivery or deeper as for muscle and joint items. Aloe vera is one of the best. It just needs a good preservative to keep it from going old too quickly...longer shelf and usage life.
But as far as the skin absorbing pollutants or undesirable items in water via the shower, lets just use simple logic and consider it a valid point.
Now go rub some garlic on you palms and see how long it takes you to become..."fully fragrant"...;)