There are no tests I'm aware of unless one has access to a lab. If someone could come up with a reliable, reasonably priced test, I bet they'd sell well. As it is, there are scores of people out there using filters that may or may not work. Good thing the waters in the wilds of N. America are actually pretty darn clean. I bet that if the waters were as contaminated with giardia as filter companies would have us think that there would be a lot more cases of illness.

HJ