When referring to people we often say, "It's what inside that counts" – and this could not be more true when trying to evaluate shower filters. Therefore in this article we will be discussing the various types of shower water filter mediums (the stuff inside shower filters that actually filter the water). We will look at each of the leading types of shower filter mediums, discuss how they are produced, explain their virtues and also make note of their inferior aspects.

Granular Active Carbon (GAC)

By far this is the most common type of filter medium in a shower water filter. It is mainly so popular because it is reliably cheap to produce and has great filtering properties. Because of it's microporosity a single gram of this material has a surface area which exceeds 500m squared, which gives it great filtering properties.

In the past GAC was produced primarily by producing charcoal from wood and coal, but these days most GAC in water filters are made from carbonaceous materials such as nutshells and coconut husk – making these products once destined for the rubbish tip a valuable resource again.

Generally most multi-stage filters of any type will include at least one layer of GAC as a filtration stage. This is the same for many shower filters. Yet it is not just water filtration that can be achieved through using GAC, it also can filter; gas, oils, chemicals and can even be used to treat poisonings and overdoses by simply investing it. As a filter it really is a miracle product, no wonder it is used so much.


  • Cheap and easy to produce from waste materials
  • Great natural filter
  • Can be used to filter almost anything from sewage to gas
  • Used world wide by governments, health agencies and municipal water treatment plants
  • Tried and true method of water filtration
  • Removers:
    • Chlorine
    • Chemicals
    • Chloramine
    • Dissolved volatile organic chemicals (VOCs)
    • Herbicides & pesticides
    • Radon
    • Water hardness; calcium, magnesium in water
    • Organic compounds
    • Stops bad smells and tastes


  • When used just by themselves, GAC filters need to be replaced quite quickly as the filter medium can get clogged up and stop filtering.
  • Filtering water through a GAC ​​filter takes time so having a large GAC filter for a shower is not a good idea because it will not give enough flow for a proper shower.
  • At very high temperatures (over 80 degrees C) GAC can start to slough out of the filter, but this is not too much of a problem with shower water filters because at 60 degrees C skin starts to get burnt. Therefore no showers will get to a heat where GAC will have this problem.

Kinetic Degradation Fluxion – KDF

This type of filter medium is the golden child of the shower filter world (it literally is golden in color as well!). KDF is a patented filter medium discovered and produced by the company KDF Fluid Treatment Inc. based in the USA. The medium was discovered by Don Heskett in the 60s and since then has been on to be recognized and utilized by many government bodies including the United States Environmental Protection Agency – who classify it is a 'pesticidal device' because of it's great ability to kill bacteria and other microorganisms.

KDF is produced in a method that specifically combines copper and zinc, this combination creates a fine golden sand like substance that creates an electrochemical reaction when water passes through it. This reaction changes the chemical make up of the harmful substances in water (such as chemicals like chlorine) and turns them into benign substances that are not harmful. Also this reaction causes heavy metals in the water to plate out (stick to) the medium's surface, therefore removing them from the water. Dangerous microorganisms such as algae, fungi and bacteria are also immediately killed when they touch KDF.


  • Long thinking
  • When used in conjunction with GAC can further the life of the GAC
  • Kills bacteria, fungi and algae which may try to live inside a filter
  • Recyclable
  • Reacts quickly so gives a good flow of water in the shower
  • Removers:
    • Chlorine
    • Kills bacteria, fungi & algae
    • Heavy metals (such as lead, mercury, copper, etc.)
    • Scale and hardness


  • Expensive because it is a patented product.

Vitamin C

Filtering water with Vitamin C is one of the newest filter mediums found in shower water filters. One noticeable difference with this type of filter medium as opposed to the above two filter mediums is that it can only be found in shower filters. Vitamin C to filter water is not found in any industrial water filter processes and has not been approved by any scientific foundations or government agencies to provide suitable water filtration needs.

Vitamin C water filters work to neautralise Chlorine found in water. The chemical is actually called ascorbic acid (otherwise known as Vitamin C) and when Chlorine comes into contact with this chemical it reacts to it and turns the chlorine into a harmless substance.


  • Very fast reaction time


  • Very unstable, when exposed to water solution it degrees in a day or two
  • Only removals Chlorine, leaving all other contaminants in water supply
  • Not fully scientifically tested or proven.

In conclusion from the above we can see that the best type of shower water filter medium is not one single filter medium, but a shower filter that incorporates multiple mediums (such as KDF and GAC). Yet no matter what type of shower filter one decides on getting, at the very least by installing a shower water filter at the very least we are protecting ourselves from harmful chemicals in our water supplies.


Source by Jenny Holiday