There is almost a water filter for any application. The most common applications are as follows.
Under counter water filters – Fits under the kitchen sink to provide a single point for drinking.
Cartridge system water filters – This filter is a cartridge housing that can be fitted anywhere. They are used as under counter to provide a single drinking point, inline system where it gets fitted to the existing pipe work under the kitchen sink and goes to the cold tap already fitted. Cartridge systems are used for sediment removal using a sediment filter cartridge.
Whole house water filters – Used when there is a need for the whole incoming water supply to be filtered.
Portable water filters – Normally used for travel, in rented accommodation if the tenant is unable to alter the sink or pipe work