There are a few options for water filters that can replace reverse osmosis. One option is a pitcher filter with an activated carbon filter. This filter will remove chlorine and some other chemicals from the water, but it will not remove fluoride. Another option is a whole house water filter. A whole house filter will remove chlorine, sediment, and some other chemicals from the water, and it may also remove fluoride. Finally, you can use a gravity-based water purifier.