Multi-Stage Water Filter Systems

Most water filter systems are made up of several water filter cartridges, each corresponding to a filtration stage. Each stage has a well-defined purpose in the filtration process, targeting specific contamination issues.

When looking to buy a water filter system, you’ll come across units with varying stages of filtration (from two-stage filters to 6+ stage filters). In many, this raises the question of how many stages should a water filter have? And whether multi-stage water filter systems are better than single stage filters?

More Filtration Stages = Better Filtration?

Systems that use more filter cartridges are believed to be better at removing contaminants, since water passes through several filter beds before it’s delivered to you. These filter cartridges can be carbon block filters, granular activated carbon filters, ceramic filters, KDF filters, reverse osmosis membranes, etc. sometimes combined in a single system.

However, too many water filter cartridges in a water filter system can reduce flow rates, increase the upkeep costs of the filter system, take up more space, and remove healthy nutrients from tap water. Therefore, when looking to buy a water filter system, the number of filters it has shouldn’t be the only factor to consider.

Depending on what it’s designed to remove, a water filter system can be single-stage or multi-stage. Single-stage systems are usually systems that have a single filter cartridge containing a single type of filter media, e.g. countertop filters, inline water filters or other under-sink water filters.

Single-cartridge filters are usually taste and odour filters that are designed to remove chemical disinfectants and their by-products.

Sometimes, single-cartridge water filters can technically be called multi-stage filters when they contain more than one type of filter media within a single cartridge. For example, the H2O US3 6 Stage Advanced Water Filter System contains sediment filter media, silver impregnated carbon, GAC, riolite, KDF creating a 6-stage filtration process within a single cartridge.

Depending on the filtration technology used, some water filter cartridges are absolutely necessary for a reliable filtration process. Thus, UV water filters will always have at least two purification stages, where the first stage contains a sediment pre-filter that removes suspended solids, while the second stage is the ultraviolet lamp that destroys bacteria, viruses, cysts and other microorganisms in tap water.

Reverse osmosis filter systems are the quintessential example of filter systems that use a multi-stage filtration process. As for the filtration stages necessary for a reverse osmosis filter, most systems will necessarily consist of a sediment pre-filter, a carbon block pre-filter, a reverse osmosis membrane, and a carbon block post-filter.

Whole house water filters also vary in the number of filter cartridges they contain, but there will usually have at least two filter cartridges, either a carbon block filter and a KDF filter, or a carbon block filter and a ceramic filter cartridge.

Things to Consider When Buying a Multi-Stage Water Filter System

A multi-stage water filter system may sound like a good idea for anyone wanting to install a water filter in their home, however, there are a few things you should be mindful of before making an investment:

Type of filter media

The number of water filter cartridges can be a good indicator of contaminant removal efficiency, but make sure that the system includes different types of filter media, and not just a single type. Having different kinds of filter cartridges in you water filter system means more types of contaminants are being removed.

Upkeep costs

More filters mean more filters to replace and higher maintenance costs. Check the filter replacement frequency and annual replacement costs for your water filter system, and if you’re happy with the numbers, go ahead and purchase the water filter system of your choice.

Flow rates

Too many filter cartridges in a system can interfere with the desired flow rates, so check the specifications of the system for expected flow rates.

Contaminant removal efficiency

Having a water filter that doesn’t remove the contaminants you need to target won’t do much for the quality of your tap water. First, find out what – if anything – is wrong with the quality of your tap water, then find a system that is designed to tackle those issues.

Necessary filters vs polishing post-filters

Not all filter cartridges in a water filter system are absolutely necessary for the filtration process. Most pre-filters like sediment filters and carbon block filters are necessary since they are used to either protect more expensive filter media in the filtration process (e.g. to protect the reverse osmosis membrane in an R.O. filter), however, most post-filters like alkaline filters or re-mineralising filters are only necessary if you need to balance the pH levels of your tap water, or you want alkaline water on tap.

Affordable Multi-Stage Water Filters at

Multi-stage water filter systems are available both for installation at point of use and whole house water filtration. The water filter systems listed below are some of our best in multi-stage water filtration:

BMB Nano Ultrafiltration (UF) Water Filter System

A compact and economic model, the BMB is a 4-stage ultrafiltration system with easy to replace plug and play components. The BMB is a tank-free filter system suitable both for residential and commercial use.


Ultrafiltration down to 0.1 micron size;

Filters with antibacterial properties;

12 month filter lifetime;

Delivers up to 300 litres of filtered water per day;

Installed under-sink, at a single point of use.

Osmio PRO-II-XL Advanced Whole House Water Filter System

This advanced whole house water filter uses a 5-micron carbon block filter and an active ceramics filter to remove a host of common tap water contaminants. It’s ideal for medium to large homes and for anyone looking for a 2-stage advanced whole house filter system.


Main filter lasts up to 3 years;

Secondary filter filters down to 5-microns;

Improves water pH;

Coconut shell activated carbon improves taste and odour of tap water;

Filter removes chemical contaminants, bacteria, toxins, fluoride and hormones.

Osmio PRO-III-XL Ultimate Whole House Water Filter System

This 3-stage whole house water filter system combines an active ceramics filter, a carbon block filter, and a GAC and KDF process media filter cartridge to remove chlorine, bacteria, hormones, fluoride, lead and many other contaminants.


Long-lasting filters and in-depth filtration;

Ideal for medium and large homes;

Environmentally-friendly ceramic filter media;

Provides softer, non-scaling water.


Testing your tap water for contaminants will be the determining factor in which type of water filter system you need for your home. If the contaminants that you want to remove cannot be removed by a single type of filter media, you need to find a filter system that combines the filtration efficiency of multiple filter cartridges.


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