(PDF) How copper-zinc water treatment systems work - Green Nest

How copper-zinc water treatment systems work
The combination of copper and zinc (patented under the trade name KDF®) in water treatment systems
removes chlorine, chloramines, iron, lead, bacteria, hydrogen sulfide, and hundreds of other problem
contaminants from the water supply. It also reduces scale and hardness.
Works Alone or in Combination
Copper-zinc can be used alone or in concert with traditional treatment processes (such as carbon and
reverse osmosis) for a synergistic blend of media. Copper-zinc assists traditional treatment by extending the life
of carbon or reverse osmosis membranes, by maintaining a bacteriostatic environment inside the filter, and by
leaving a residual of copper and zinc hydroxides in the treated water to discourage bacterial growth.
Lasts Longer than Carbon
With a lifespan of 10 to 20 times that of carbon, copper-zinc is the most efficient, longest lasting, and lowest
maintenance filtration media on the market. It removes the weak link in most water treatment systems: the
monitoring and maintenance and component replacement required by these systems.
CuZn systems perform better because the compact, dense copper-zinc alloy has no pores that plug up, is not
soft like carbon, has no membranes to replace, remains bacteriostatic, and can be easily backwashed for years
of use.
Filters by Catalytic Action
CuZn media functions by catalytic action, using the age-old redox (reduction-oxidation) principle of dissimilar
metals. Water containing dissolved oxygen, minerals, and organic materials enters a bed of the copper-zinc
alloy, with the copper becoming the cathode and the zinc becoming the anode.
The space between each granule of alloy in the media bed becomes an electrolytic cell. The water and
contaminants act as electrolytes.
As contaminants and oxygen pass through, a reaction takes place, causing zinc hydroxides and copper
hydroxides to form in controlled amounts. These controlled releases of copper and zinc oxides (chelatable by
the body) are carried into the filtered water and provide hostile conditions for algae, fungus, and bacteria growth.
Eliminates Hard Scale
Within a water system, calcium and magnesium can adhere to plumbing and water appliances by forming
crystalline scale structures. These become hard, interfere with heat transfer and eventually cause loss of water
flow and pressure.
Copper-zinc reshapes these hardness ions so they cannot adhere to each other or to the inside of plumbing.
Instead the calcium and magnesium ions remain soluble in the water, thus reducing scale while adding life to the
water.

(Water without these minerals is flat and can be aggressive, since water in its most natural state contains
minerals such as calcium and magnesium, picked up from the earth as it filters through rock strata.)
This scale reduction feature is ideal for cooling towers, hot water heaters, water lines, plumbing, ice-makers,
fountains, and other water-using equipment and appliances.
Removes Hydrogen Sulfide
Hydrogen sulfide is present in many U.S. water supplies. Recognized by its rotten egg odor and taste, it is a
poisonous gas that can, in large amounts, cause nausea and illness or death. It is also corrosive to metals,
which is especially serious in older plumbing systems that used lead-based solder.
When hydrogen sulfide passes through copper-zinc media, spontaneous oxidation removes the hydrogen
sulfide by creating zinc oxides and zinc sulfates. Zinc oxides and zinc sulfates are defined as food supplements
and nutrients by the Food and Drug Administration.
(During the copper-zinc filtration process, minuscule traces of zinc and copper are released into the water. In
proper amounts, both copper and zinc are necessary for healthy body functions. The trace amounts found in
CuZn filtered water are a small percentage of the minimum daily requirement for these minerals.)
Meets NSF, EPA Standards
In 1992, the Environmental Protection Agency ruled that copper-zinc, patented as KDF-, qualifies as a
mechanical device. This means the media imparts nothing harmful to the water. The National Sanitation
Foundation tested KDF® and found it to be in compliance with its Standard 61 for water treatment plant
applications and Standard 42 for aesthetic effects (taste, odor, chlorine reduction).
Removes Heavy Metals
Copper-zinc systems are excellent at removing heavy metals, often by electroplating them to the media's
copper-zinc granules. Under normal circumstances, CuZn filtration removes 90 to 98% of heavy metals,
including lead, iron, arsenic, and cadmium.
Works With Chlorination
When iron, hydrogen sulfide, or bacteria are present in large concentrations, CuZn filtration can be preceded
by chlorination and retention time. Chlorination oxidizes these contaminants and assists the copper-zinc media
in their removal. The copper-zinc, of course, then removes the chlorine and remaining contaminants from the
With carbon-only systems, this combination of chlorination and filtration is not efficient because the carbon is
quickly depleted when high levels of chlorine pass through it.
Works With Carbon

Many CuZn systems use carbon filtration in concert with chlorination and copper-zinc filtration to treat water
with high levels of organic contaminants which carbon is excellent at removing.
Because the carbon is not removing chlorine (the copper-zinc does this before the water reaches the carbon)
and because the copper-zinc provides a bacteriostatic environment, carbon's life is greatly increased. (Bacterial
fouling of the carbon media is a serious problem in carbon-only water filtration and requires frequent media