Resource Guide to Whole House Water Filters that Remove Chloramines


There are many  styles of filters that remove chloramines from city water.  Any carbon filter will reduce chloramines, but a specialty carbon called “catalytic carbon” does the job much faster and more completely than conventional filter carbon. “Centaur” is the brand name of the first and most respected catalytic carbon, but there are other brands that do an excellent job.

Filter carbon can be arranged in two forms.  Granular carbon has the consistency of coffee grounds and is most commonly used in tank-style filters.  Carbon blocks are made of powdered carbon that is compressed into a solid board-like substance. Blocks are used in the form of compact, replaceable cartridges, which are changed periodically the same way that you change the filter in your furnace or air conditioner.   Both styles have their advantages.  Carbon blocks are more efficient per size, but they also restrict water flow much more.

The most critical design feature in a chloramine filter is “residence time.”  This refers to the amount of time that the water actually contacts the carbon.  It takes longer to remove chloramine than to remove chlorine, so the water needs more time in contact with the carbon.  Contact time depends on the size of the bed or the filter cartridge and the rate of flow.  Obviously, a large home with several residents will use more water than a small home with two inhabitants.  The larger home will need a larger chloramine filter.

Because of the way catalytic carbon works, if the filter is adequately sized it will not only do a better job, but the filter medium–the granular carbon or the carbon block– will also last much longer.  Here’s a chart that will help in sizing.  It is used by water treatment professionals to make an educated guess on filter and softener sizing.

Number of Residents 1-2 Bathrooms 2-3 Bathrooms 3-4 Bathrooms 4-5 Bathrooms
1-2 5 GPM 7 GPM 10 GPM 12 GPM
2-4 7 GPM 10 GPM 12 GPM 14 GPM
5-6 10 GPM 12 GPM 14 GPM 18 GPM
7-8 10 GPM 12 GPM 14 GPM 18 GPM
9-10 12 GPM 14 GPM 18 GPM 20 GPM

This chart is intended as a suggestion only. The nature of the building and the individuals who live there must be taken into consideration. It is intended for use in sizing for standard residential dwellings. Mansion dwellers must look elsewhere for advice.  Please note that these sizing rules are frequently violated and so far no one has been arrested.

Within the two basic carbon styles, granular and carbon block, many design variations are possible.  To illustrate, here are some page links to products on the Pure Water Products website.

The “Chloramine Catcher” is a series of top quality backwashing filters in residential sizes.  The “gallon per minute” ratings are the most conservative–based on the Centaur manufacturer’s recommendations for dialysis use–so they are frequently violated for residential use.

The Fleck 5600 Backwashing Filter Series contains a more economical backwashing filter with a less expensive control system than the 2510 control used in with the Chloramine Catcher. It comes in one size only –10″ X 54″–which is suitable for homes with two or three people and a couple of bathrooms.  Note that it comes in a “green” low water use unit as well as the standard.  See products BW003 and BW571.

In/Out Upflow filters are tank style filters similar to backwashing filters but there are differences.  In/out filters don’t backwash so they don’t need electricity or a drain connection.  The service flow pattern is down to up rather than the up to down flow of the backwashing filter. Since they have no way of cleaning themselves of sediment that gets into the tank, they must be protected by a sediment filter, and it’s a good idea to install a sediment filter after the upflow filter to assure that no carbon particles leave the filter and get into service lines.

All of the tank style filters above eventually need carbon replacement.  There is no fixed rule on this, but a reasonable replacement expectation would the three to four years.

Cartridge Style Filters work great for chloramine reduction, especially when equipped with a cartridge that’s specially formulated for chloramine removal.  These filters are limited to about 4 gallons per minute service flow, but can be easily installed in multiples, in parallel, to accommodate higher service flow needs.  These filters are more economical to purchase initially, but the ongoing expense of cartridge replacement is greater.  Follow these links  for information about multi-filter installations and  the most popular chloramine-specific cartridge.


Here are answers to a couple of questions that always come up in chloramine discussions.

Catalytic carbon removes chlorine and other chemicals the same as regular carbon.  You don’t need an additional filter for chlorine.

The chloramine reduction process is a catalytic operation that breaks the bond between chlorine and ammonia and converts the chlorine to harmless chloride.  What happens to the ammonia is a much more complicated issue; the removal of ammonia traces can be accomplished separately with a water softener, but special conditions apply.  By definition,  chloramine removal means getting rid of chloramine and does not take by products like ammonia into consideration.

Chloramine has been in use in the US since the 1920s and many US water supplies have had it for decades.  It was not invented by the Devil or by liberal Democrats to bring you to grief.  There are many sound reasons why for some cities it is a better disinfectant than chlorine. However,  for those who have allergic reactions to it, it can be a real menace.  It is also a big problem for aquarium owners.  Removing chloramine is more a challenge than removing chlorine, but it can be done and life will definitely go on.

Removing chloramine from drinking water is much easier than removing it from all the water entering the home.  The best plan is a filtering device with lots of carbon–the more the better.  Chloramine specific cartridges are available in drinking water sizes, though standard carbon is usually very effective when it gets the water at drinking water speed of a half gallon a minute or so. Most reverse osmosis units remove chloramine easily.

Chloramine Plus Carbon Block Filter.  High quality carbon block filters are very effective at removing chloramines.