These British Berkefeld gravity filters are great. They allow you to perform high-quality water filtration on your counter top using gravity alone. The ceramic filters inside last for years, and need cleaning only every three months or so. They’re pretty easy to operate too — you just pour water in the top half, it the water drips down the bottom half. After a few hours you have gallons of ready-to-drink water. Link.
Gravity Filters: No Need for Bottled Water