They do, and they're expensive. But, they last a long time. I recently replaced a set of filters in mine, that I used for years. I figure it probably cost me about two cents a gallon to filter my tap water. Compare that with the cost of buying bottled water, and there's just no comparison.

I keep a spare Big Berky and two spare filter sets with my survival supplies. That gives me one less thing to worry about--and that makes it well worth the price.

Onward and upward,
airforce