Of all the available water filter types, whole house filtration systems are the most economical and efficient way to get filtered water in your entire house. With a whole home water filter, you’ll get the same quality filtered water at the tap in your bathroom as the one flowing from your kitchen tap. Point-of-entry filters have the advantage of being installed at water’s point of entry, thus, filtering all the water that goes into your home.


Most water filters are made up of multiple filter cartridges (usually containing different types of filter media) that act as stages of the filtration process carried out by your filter system. It is not uncommon for whole house filters to use several types of filter media to deliver a more in-depth filtration. But how many stages are required for a whole house water filter to eliminate most types of contaminants?

Filtration stages of a whole house water filter

If your whole house water filter is a reverse osmosis system, most water filter experts agree that it should have at least 4 stages – 1 sediment pre-filter, 1 carbon block pre-filter, 1 reverse osmosis membrane, and a carbon block post filter. For more details about the compulsory and optional filtration stages of a RO filter, you should read our article on the filtration stages a reverse osmosis system should have.

If your whole house filter is an UV water filter, you need at least 3 stages of filtration – 1 sediment pre-filter, an UV filtration unit, and a carbon block filter, preferably in combination with active ceramics to remove chemical contaminants, lead, pesticides, herbicides, etc.

Whole home filtration units that don’t rely on reverse osmosis filtration or UV purification, need a filter cartridge that deals with chlorine removal, VOCs, pesticides, herbicides, taste and odour improvement (e.g. carbon block filter), and a further filter cartridge for bacteria and heavy metal removal (e.g. active ceramics). Simple taste and odour improvement filters usually consist of two filtrations stages that involve a sediment filter and a carbon block filter.

While the number of filter cartridges present in your system can be a good indicator for the level of filtration that the system is capable of, a better indicator of a system’s efficiency is the type of filter media that it contains. Water filter manufacturers can often create highly advanced filter cartridges that contain a blend of different filter media that are capable of tackling a wide range of contaminants. For example, the Doulton Ultracarb 10 Inch Short Mount Candle removes pathogenic bacteria, heavy metals, chlorine, iron and hydrogen sulphites, cysts, cryptosporidium, giardia, VOCs, asbestos fibres, etc. Therefore, this filter cartridge is single-handedly capable of dealing with a wide range of contaminants.

The smartest way to decide how many stages your whole house water filter system should have is to test your tap water and see which are the prevalent contaminants that need to be removed, and find a filter system that is capable to target those specific contaminants.