If the water is going to be reasonably clean ( not too many trees close by ) you could try a duel gradient cartridge using only one housing. This cartridge has an external filtration size of 25 microns and merges to a final filtration off 1 micron at the inner core. Many people do use these cartridges and it can be an economical method avoiding the need for a second housing & cartridge.
Greenway 10s model with 25 mm ports suited to homes with up to two or more showers and water flows up to 60 litres per minute.
The UV chamber is pre mounted on a bracket including a stainless steel connection hose between the filter casing and the UV chamber, as well as a stainless steel water shut off valve as in the picture.
