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Is there KDF in your water filter?

If you’ve ever shopped for a water filtration system for your home, you’ll know that there are a lot of different systems out there!  Starting with the size, you can go from pitcher (1-2 liters) to countertop, to under-counter, to whole-home systems.  Then, there are the different methods used to remove different pollutants.  Do you want a passive system that just uses gravity, or a system that uses the water pressure to filter, and/or a system that back-flushes contaminants to “clear” the filter?

Many filtration systems use granule-type media, which can be made from activated carbon, catalytic carbon, copper and zinc particles, mixed media like gravel and resin, activated aluminum or manganese dioxide.   Copper and zinc particles are what is used in kinetic degradation fluxion (KDF) filters, and depending on the ratio and granule size, KDF media can reduce the levels of water-soluble heavy metals, chlorine, iron, and hydrogen sulfide. It also manages scale, bacteria, and algae in the water. (aquasana.com)

Kinetic degradation fluxion describes how this type of media purifies water.  It works in a reduction/oxidation process (also known as “redox”) in which, as the water travels through the media, some molecules gain electrons (reduction) and some molecules lose electrons (oxidation).  Although this sounds counter-intuitive, reduction and oxidation refer to the oxidation states of the atoms, where gaining an electron reduces its oxidation state, and losing an electron increases its oxidation state.  The oxidation state is the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom. (Britannica.com)  For example, as lead, hydrogen sulfide and chlorine (found in many water supplies) flow through KDF media, some of the harmful contaminants are changed into harmless components, while others are electrochemically bound to the KDF media: (waterfilterguru.com)

• Soluble lead cations (positively charged ions) are reduced to insoluble lead atoms, which are electroplated onto the surface of the media (they stay in the filter and can only be removed by recycling it) . (KDF Reticulated Foam)

• Dissolved chlorine gas is reduced to water-soluble chloride ions, which pass through with the water as harmless ions that no longer have oxidation properties.  The KDF media donates two negatively charged electrons to each molecule of chlorine to reduce it to the lower oxidation state of chloride. (What are KDF Process Media and How Do They Work?)  (You can check out an animated visual of the transformation of chlorine gas into chloride ions on the same page!)

• Hydrogen sulfide: the copper in the KDF media loses an electron and the sulfur gains an electron, so that copper sulfide and water are formed. The copper sulfide is insoluble in water and can be backwashed off the KDF filter media.

As you can see, this type of filter works on a lot of different contaminants, and even microbes.  Copper and zinc are anti-microbial metals.  They kill bacteria by direct electrochemical contact and by the flash formation of hydroxyl radicals and hydrogen peroxide, both of which interfere with a microorganism's ability to function. (LennTech.com)  Because other filters can be more prone to microbial growth (like activated carbon), using a KDF filter before the carbon filter prolongs the life of the carbon filter.   

KDF was invented in 1984 by American Don Heskett “accidentally”.  He used a brass ballpoint pen to stir some chemicals and discovered that it removed chlorine from water.  He worked on the formulation for several years and patented it, also forming the KDF Fluid Treatment (KDFFT) company.  Raw KDF media are produced by KDFFT and sold to many filter manufacturers, to be used alone or layered with other media in their water filtration systems.  There are 4 types of media produced: KDF 55 (55% copper and 45% zinc, removes chlorine, heavy metals and bacteria), KDF 85 (85% copper, 15% zinc, best for iron and hydrogen sulfide), KDF Fines (best for chlorine and bacteria removal when incorporated with other media) and KDF Coarse Mesh (for reduction of heavy metals and chlorines).  (KDF Products)

The benefits of KDF media are many:

• It removes a wide range of contaminants

• It is cost effective.  KDF media can be replaced every 9-12 months, or if the system allows and you have the means, can be backwashed and reused for over 6 years!

• It can be recycled. 

• It can be used in warmer water than other media (for example in showerheads or dishwasher feed water, whereas activated carbon cannot be used in warm-water applications)

• It releases no toxins into the water, so is completely safe. (KDF doesn’t require registration by the EPA as other “pesticides” do, like silver-impregnated carbon.)

Disadvantages include:

• Periodic backwashing is required unless you prefer to just replace and recycle the filter. Unfortunately, backwashing must be done at 30 gallons per minute, or the media will not be adequately flushed.  In places where water is expensive or scarce, this would be difficult to maintain.

• KDF media doesn’t remove organic chemicals such as VOCs, pesticides and herbicides, organic cysts, nitrates, fluoride, viruses, arsenic, and pharmaceuticals, so you’ll have to add another type of filter if these are present.  (waterfilterguru.com)  It also doesn’t remove chloramines (some water suppliers disinfect with chloramines instead of chlorine, which are very difficult to remove).

“Rust” in your sinks and toilets?  Iron in your water can mean iron bacteria in the water

Wait–is that rust in my toilet?  Why is the toilet looking rusty?  You might initially think that the pipes supplying the water might be rusting, and that could be a problem (however, it’s rare).  But if you know that there are no iron pipes supplying your water (if you live in the country with your own well), then you know that pipe rust is not the source of the problem.  Most likely it has to do with high iron content in the water itself, and a certain bacteria that consumes iron. At least 18 types of bacteria are classified as iron bacteria, long thread-like bacteria that “feed” on iron and secrete slime. Unlike most bacteria, which feed on organic matter, iron bacteria fulfill their energy requirements by oxidizing ferrous iron into ferric iron. (Iron Bacteria in Surface Water). 

Iron bacteria are small living organisms that naturally occur in soil, shallow groundwater, and surface waters. These bacteria combine iron (or manganese) in the soil, and oxygen to form deposits of "rust," bacterial cells, and a slimy material that sticks the bacteria to well pipes, pumps, and plumbing fixtures.  These iron bacteria don’t cause disease, but they can create an environment where other disease-causing microbes can grow (like coliform bacteria).  Iron bacteria can get into the well when the water in the well comes into contact with the soil surrounding it, or lakewater, or any rivers and streams.  (Iron Bacteria in Well Water)

If you haven’t had any work on your water system done, and you’re still suspecting the bacteria are feeding on iron pipes, here are the most common types of pipes (from 7 Types of Plumbing Pipes Used in Homes):

1. Rigid copper pipe (water supply)

2. PEX pipe (water supply)

3. PVC pipe (water supply and drains)

4. ABS pipe (drains and vent lines)

5. Flexi Pipe (water supply)

6. Galvanized steel and cast iron (outdated for water supply and drains)

7. Black pipe (only used on natural gas lines)

So, you can see that out of the 5 water supply line types, only 1 has iron in it (#6) and those are considered outdated.  The cast iron and steel pipes that were used in the 1950s have gradually been replaced by one of the other plastics mentioned above.  (A Brief History of Pipe Materials)  Therefore, if your home was built after the 1960’s, it would be very common for you to have iron in the water supply lines. 

Other than causing brown stains, iron bacteria can also cause the following (Iron Bacteria in Well Water):

• Smells: Swampy, oily or petroleum, cucumber, sewage, rotten vegetation, or musty smells, which may be more noticeable after the water has not been used for a while.

• Colors: Yellow, orange, red, or brown stains and colored water, or a rainbow colored, oil-like sheen.

• Deposits: Sticky rusty, yellow, brown, or grey slime, or “feathery" or filamentous growths (especially in standing water).

These are not the kinds of things you want to see in your sink or toilet!  It can also have detrimental effects on any water softening system, making the water running through it to have an off taste.  To confirm that the problem is iron bacteria, you can get the water tested by a lab.

If you do have iron bacteria, and states like Minnesota have a lot of it, it can be hard to get rid of.  Here are some steps you may consider: 

• If you have a heavy concentration of iron bacteria, the best first step is to have the contractor remove and clean the pumping equipment, and scrub the well casing with brushes.  Make sure that they do not lay any of the equipment on the bare ground, as this could re-contaminate it!  

• Next is chemical treatment, which is also for minor contaminations.  Treatment involves 3 steps: disinfection (or oxidation), retention time, and filtration. (How to Remove Iron Bacteria in Your Water)  Chlorine (bleach), hydrogen peroxide and ozone are frequently used.  Although many companies call all three of these “disinfectants”, the fact is that only chlorine is a disinfectant; hydrogen peroxide and ozone are oxidizers.  Disinfection is the act of killing bacteria, while oxidation causes a molecule, atom or ion to lose an electron (which also kills bacteria as a consequence).

• Chlorine (bleach): Although bleach is cheap and will disinfect, its reactions to organic matter that may be in the water are not good–like haloacetic acids (HAAs) and trihalomethanes (THMs), which are classified as possible human carcinogens.  For more information on these byproducts, check out our article here.  

• Of the two remaining, ozone is a stronger oxidizer than hydrogen peroxide, but hydrogen peroxide systems are less expensive and more readily available from water treatment companies.  According to USWater, extreme amounts of iron and hydrogen sulfide can be removed from the water supply effectively and consistently, it does not need a “contact tank” for retention time, and it does not cause maintenance issues with injection pumps as chlorine does.  (Chlorine or Hydrogen Peroxide – Which is Better for Treating Water?) does not have these byproducts and in addition, has several benefits: it can also rid water of hydrogen sulfide (H2S) smells (rotten eggs), and activated carbon filters used after disinfection last much longer than when used with hydrogen peroxide than with chlorine. (Eliminate Well Water Odors: Four Reasons Why Hydrogen Peroxide Water Treatment Is Best)  According the to Minnesota Rural Water Association, potassium permanganate is also a strong oxidizer that is in common use in Minnesota to remove iron and manganese. (Iron and Manganese)

• Retention time is needed for chlorine to work, therefore the chlorine must sit in the well for a certain period, or if you are using chlorine as a continuous disinfectant, a holding tank is usually set up, with the size being dependent on your household’s normal flow rate (water usage rate).

• Filtration is necessary to remove by-products (in the case of chlorine) and iron products (in all cases).   When chlorine contacts iron in the water, it changes the iron from a ferrous state to a ferric state, making it an insoluble particulate.  This is the state that can be easily filtered.  There are various types of filters available, the most common being activated carbon.  Reverse osmosis and some other types of filtration can remove iron from water without oxidation, and treating your water from the point it enters your home is important for all your appliances, but the iron bacteria may still thrive in your well and cause clogs up to the water treatment point. Iron can clog wells, pumps, sprinklers, dishwashers, and other devices over time. (Iron in Well Water)

If you notice these signs of brown or different colored stains, bad smell or slime deposits in your sinks or toilets, it’s a good idea to get your water tested for iron.  If iron bacteria are present, it’s likely a common problem in your area, and there are local companies who can provide the equipment needed to remove it.  However, it’s best to do your own research on these solutions to make sure that a company doesn’t try to sell you unnecessary equipment (such as a retention tank for a hydrogen peroxide system), and also it’s a good idea to get references and reviews from actual customers.