The water filter is readily available for refilling our thirst depleted water bottles. This is a very slick tool that saves us from the giardia lamblia intestinal parasite that is commonly found in lakes and streams in Western Canada. If infected, it can cause giardiasis (also known as beaver fever) which can cause diarrhea, abdominal cramps and weight loss, not something you want to have to worry about when you're canoeing from site to site (and outhouse to outhouse) each day.