I have been told that you have to ingest the water in order for the giardia to get into your system, so it would seem to me that washing your body, or swimming and not swallowing the water (especially if you don't swim with your face underwater) would present a minimal risk, if any.  The organism needs to get into your intestinal tract, not just get on your skin.

Tubing is a concern, and one I do worry about.  Since we wash dishes with either boiled or filtered water and air-dry them if possible, I hope we have taken adequate precautions.

We have been going for 40 years, nearly every year, and we used to drink from the lake.  Then we tried iodine tablets (ick), and boiling (works fine, takes a lot of time and fuel), and finally filtering. 

We look at filtering as just a bit of insurance, since we don't want to have our trip home, which is usually quite leisurely and takes several days, or our first few days at home after a trip spoiled by a severe illness.  And of course, in our case, now that my husband has had a kidney transplant, the nephrologist at University of Michigan hospital has told us that it is only common sense to filter the water for giardia, since it is a serious health threat for him and could be even life-threatening (as he is immune suppressed due to his medications.)  She also said to us that she feels it is necessary for anyone to do in the BWCA, and she is a person with BWCA experience, not one of those clueless doctors who has never been there.  ;)

I know that a lot of people go to the BWCA and the Q for years, drink the water from the lake and don't get sick.  I also know, and have talked to some of them, that some people do contract giardia and they are very ill.

Personally, I would like to try to lessen my chances. I don't like raging diarrhea very much.   :P