Don't let the blue dye test fool you into thinking First Need takes out chemicals, because it most certainly does no such thing. It is able to take out viruses where filters do not. It contains activated charcoal that does the job of removing tastes.

It is unnecessarily, heavy, has a shorter life span than many filters, and would be my choice for international travel. The directions instruct you that in some cases you should add iodine to the water - which says that is is not infallible.