Water Ionizer Pre-Filtration Basics

22/06/2011 , by Admin No Comments Filtration

Of all water ionizer customers in the United States, only about ten to fifteen percent will use any sort of pre-filtration system with their water ionizer.  Of those that opt for some sort of pre-filtration, most are addressing issues related to well water or concerns about fluoride.

Every water ionizer will have an internal filtration system that is rated for 99% chlorine removal at the least.  Most have a single multi-stage filter for effective removal of chlorine, VOC’s, heavy metals, and other common contaminants.  Companies like Tyent have dual internal multi-state filtration systems.

In most cases, the internal filtration systems found in water ionizers effectively remove the most common contaminants making the water safer for drinking prior to ionization.   These filtration systems are widely accepted as effective with no need for any sort of pre-filtration unless there are specific source water issues – like high iron or heavy metal content, hydrogen-sulfide (common in well water and responsible for a “rotten egg” or “sulfur” smell), excess sediment or particles or issues created in the internal filtration system courtesy of additives used by water treatment plants.

Still, some customers will opt for a pre-filtration system either to address specific needs or concerns or to extend the life of their internal filters.  In many cases, pre-filtration can extend the life of your internal filters by 50 to 75 percent.

Here is a rundown of the most common pre-filtration options and a guide to what each removes…

Carbon Block, GAC, Coconut Shell Carbon

Carbon is the most common filtration media available.  It comes in carbon block and granulated forms (GAC) and effectively removes organic compounds through absorption and residual disinfectants like chlorine and chloramines, through catalytic reduction.  Coconut shell carbon is considered the most effective form of carbon but you can expect to pay around 20 percent more.

Carbon filters are basic and typically used in conjunction with other types of filters like KDF, activated alumina and sediment filters.

Adding a carbon pre-filter to your water ionizer can extend the life of most internal water ionizer filters by about 50 percent.  Depending on the installation it can also filter cold water coming through your tap.  If you are using tap water for cooking instead of your water ionizer, you have the added benefit of “chlorine-free” water for cooking.


KDF or KDF-55 filters are most commonly used for treating well water.  The most common issues with well water are heavy metals, lime, and hydrogen sulfide which is responsible for that “rotten egg” or sulfur smell in the water.

KDF or “Kinetic Degradation Fluxion” filters use an oxidation/reduction process using ion exchange to convert contaminants into harmless components.  KDF can be used for elimination of chlorine and heavy metals.    It is also known to have a mild effect with regard to eliminating bacteria, algae and some fungi.

KDF is also chosen for customers in homes with older metal plumbing for reduction of the metal.   In these situations, when the source water is from a municipal supply, KDF is used in combination with a carbon filter to extend the effective life of the KDF’s chlorine removal capacity.

When used as a pre-filter for a well-water source, the KDF filter can extend the life of your internal filter by about 50 percent.  If used with a municipal water source along with a carbon filter you can extend the life of your water ionizers internal filter by up to 75 percent.

Depending on your installation, the system can also filter water coming through your tap for cooking.

Activated Alumina

Rated by the EPA as the “best available technology” (BAT) for removing fluoride and arsenic.  While most often used for fluoride reduction, activated alumina also removes arsenic and lead which are both found at some level in most natural water sources.  The EPA has set guidelines for maximum levels allowed in treated water.

Activated alumina removes fluoride through absorption.  Higher pH levels in the source water reduce the effectiveness of activated alumina and flow rate can also be a factor.  Activated alumina is widely used in both homes and industry for removal of arsenic and fluoride.

There is some discussion about whether or not the activated alumina leaches aluminum into the water during filtration.  For this reason, many choose to add a KDF filter after the activated alumina filter.

An activated alumina cartridge alone won’t extend the effective life of your water ionizer’s internal filters.  When used in conjunction with a KDF filter you may be able to extend the life of your water ionizer’s internal filter by about 50 percent.

Sediment Filters

Most commonly used for well water or older homes, sediment filters collect excess particulates that can decrease the effective life of your water ionizer’s internal filtration system.   In the long run, excess sediment may cause additional maintenance issues for your water ionizer.

You won’t extend the life of the filters inside your water ionizer by using a sediment pre-filter but you will ensure you are getting the most out of them.  If you know you have excess sediment in your source water, a sediment pre-filter will help protect your water ionizer investment.

Reverse Osmosis

In most cases, you can double your water ionizer’s internal filter life by using it in conjunction with a reverse osmosis system.   While on the surface this sounds like you’ll be saving money you should consider that, along with the contaminants, your RO system will also remove the minerals necessary for proper ionization.

Adding minerals back into the water for proper ionization will be necessary and to do this you will need to install a “remineralizing” pre-filter.  Depending on the effectiveness of your RO system you’ll need to replace your “remineralizing” filter every six to twelve months.  In some cases, customers have found that they are replacing this filter every three to four months.

Choosing a Pre-filter

A good water ionizer dealer will be able to help you determine the best options to address any concerns you may have about your source water.  A recent water report is always helpful but not always necessary.

If you have questions about pre-filtration, ask your water ionizer dealer.  They should be able to answer your questions or help you find the answers you need.

water ionizer


Leave a Reply