We took the Sawyer S2 Foam Filter with us on a two-week trip to Mexico, where we knew the tap water was not recommended to drink. The S2 squeezed the heck out of many liters of water and kept us healthy throughout. It is not the easiest or quickest model to use, but the fact that it is effective against viruses and other microorganisms is very comforting, and it was a no-brainer to throw in our luggage. We could bring it along with us on our daily excursions to drink from, and use it in our AirBnB to filter water into other vessels. We did notice some particles from the foam filter in our water that changed our water to a bluish color and were a bit disconcerting to drink.
To see how the Sawyer S2 stacks up to its competitors check out the Best Backpacking Water Filter Review.