Granular Activated Carbon Drinking Water Filters

GAC (Granular Activated Carbon) drinking water filters from Delta Pure Filtration reduce a range of dissolved contaminants such as chlorine, THMs and heavy metals from water, depending on the media packed into the cartridge. The filter cartridge is installed in standard DOE (double open end) style housings, and is used to improve the taste and odor of water, or to protect downstream RO membranes which can be damaged by chlorine.

Delta Pure standardly packs these capsules with coconut shell activated carbon to meet a common requirement for chlorine reduction, and we will optionally employ a different user-selected filter medium or combinations of media or resins for removal of specific contaminants. Delta Pure offers filter users a choice of media because not everyone’s water is the same.

Benefits of Water Testing

No single water filter technology is automatically good for “any and all contaminants.” An ill-advised approach might be to say “I don’t know what contaminants my water has, so I will try to choose a filtration system that removes everything.” Such an approach can be ineffective because no filter or filtration system automatically removes any and all known and unknown contaminants from all possible water sources, so in this type of “blind” approach there is a danger of not removing a contaminant that needs to be controlled or eliminated.

On the other hand, adding the capability to remove contaminants that are not in your water, and that are not likely to appear in your water in the foreseeable future, can be wastefully expensive.

Having your well water tested by an expert is very important. Water users who obtain their water from a public utility can obtain information on water quality from the utility – such information is readily available on the internet and regularly mailed out to utility customers.

If you use water from a public utility, it is good to read the water report and other mailings to learn about what is in the water, what is added to the water, and what water treatment changes are being planned. Such water reports sometimes reveal that undesirable excursions in water quality have occurred.

Confident “do it yourselfers” can purchase a water test kit from a local hardware store; these easy-to-use kits can be of some limited benefit to learn about some types of contaminants.

The Benefits of Chlorine and THM Removal

Most municipal water utilities chlorinate water to kill off many kinds of disease-causing bioburden (germs) in the water. (Chlorination is not effective against all microbial threats, however.)

Activated coconut shell carbon is our most popular filter packing material because it excels at economically reducing chlorine in drinking water, thus improving taste and odor, and because it reduces disinfection byproductsi such as tri-halomethanes or THMs caused by chlorination. THMs can cause cancer and other diseaseii – so people want to get them out of their drinking water!

Chloramine Removal

Some city water supplies have chloramines instead of chlorine, and coconut shell carbon is not very effective at removing chloramines. Over 20% of US water utilities do add chloraminesiii because chloramines help the utilities to comply with US EPA rules for disinfection byproducts (such as THMs) and because chloramines have a substantial “residual” – that is, chloramines stay active a long time without dissipating, through miles of underground piping, even coming out of your faucet.

The number of municipalities using chloramines has been increasing. Water users who do have chloramines and want to remove them will typically opt for “catalytic carbon” which is superior to standard coconut shell activated carbon for this task. Suppliers of catalytic carbon tell me that catalytic carbon also removes THMs.
“Residual,” whether it is chlorine, chloramine, or some other disinfectant, is beneficial for killing many types of microbes that might otherwise cause disease, but many folks just don’t want it in their water, because of taste, smell, feel on the skin and hair when bathing, or other concerns. Chloramine is also notorious for causing damage to plumbing systems in homes and commercial buildings.

Removal of Heavy Metal and More

Many of our customers are asking for KDF® 55 Process Media (trademark of KDF Fluid Treatment Inc.) which its manufacturer claims will “safely reduce or remove chlorine, iron, hydrogen sulfide, heavy metals, and bacteria from… water”iv and in response we now make a premium version of our GAC filters containing KDF media.

The manufacturer of KDF media provides specific examples of real-world applications where the KDF media has reduced lead, mercury, iron, rotten-egg-smell-causing H2S, chlorine and scale.v

The bacterial reduction claims of KDF are often mis-understood. According the manufacturer, the EPA does recognize KDF® 55 as a “pesticidal device” for it bacteriostatic value (ability to stop bacteria from replicating but not always effectively killing the bacteria) in carbon Although KDF Process Media can help prevent the proliferation of bacteria within a filter, it does not automatically kill all the micro-organisms passing through it.

KDF 55® Process Media were certified by NSF International to its Standard 61 for drinking water.vii NSF/ANSI Standard 61 is an independent, non-governmental standard which is nonetheless recognized by many governmental bodies (within the USA) regulating drinking water, and it sets heath-effects criteria for many drinking water components, including filter media and ion exchange resins.viii

Sediment and Pre-filtration

While there is some coarse sediment pre-filtration inside each GAC cartridge, the GAC filter is not meant for heavy-duty removal of sediment and dirt particles. Where sediment, rust particles, sand, and other particulate matter are of concern, a pre-filter upstream of the GAC filter is recommended.

An economical pre-filter will generally increase the life of the more expensive GAC filter cartridge. Where removal of bacteria, protozoa, cysts or other bioburden is desired, a qualified filter should be added as an additional stage – usually downstream of the GAC filter.

Contact Delta Pure

To discuss your specific water system requirements, find the name of your closest Delta Pure Filtration distributor, or learn more about GAC and other filters, contact Delta Pure Filtration.

Notes: (1) “typically effective” does not guarantee complete removal. (2) Adsorptive media will cease to adsorb impurities when they become saturated or “used up.” (3) This is not an exhaustive list of all relevant contaminants. (4) This table is for general information only and filters should be selected and evaluated on a case-by-case basis by qualified persons.

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[i] “Trihalomethane Removal with Activated Carbon”; Robert J. Potwora, Water Conditioning and Purification; June 2006

[ii] What disinfection byproducts does EPA regulate, how are they formed, and what are their health effects in drinking water at levels above the maximum contaminant level?

[iii] Chloramines in Drinking Water at EPA.Gov website;, as accessed June 30, 2014.

[iv]; as accessed July 7, 2014

[v] as accessed July 23, 2014

[vi]; as accessed July 23, 2014

[vii]; as accessed July 23, 2014

[viii]; as accessed July 23, 2014