WATER NEWS
Two Eye-Opening Films about Water
December 12th, 2008Two exceptional films about water, our planet's most essential resource, are being presented at the VanCity Theatre, 1181 Seymour St in Vancouver this week, December 12-18. BLUE GOLD: World Water ... More »
What is KDF?
KDF is an alloy of copper and zinc that is used in most shower filters and some drinking water filters. It removes free chlorine from water by reversing the electrochemical process that originally produced the chlorine. Chlorine is created by separating chloride ions from sodium in a brine solution.
Because copper and zinc are dissimilar metals, a molecular tension is created between the two metals as water passes through the KDF media. This galvanic action produces a mild electrical charge enabling the chlorine to combine with a metal ion, in this case zinc. The result is the formation of soluble zinc chloride which is washed out of the filter and is harmless to humans. Free chlorine is extremely reactive and seeking to re-unite with another element. In the absence of an electrical charge it combines with organic matter.
An excess of turbidity in the incoming water can interfere with this galvanic action, lessening KDF’s ability to remove free chlorine. For this reason, the life of a KDF filter is more closely related to the particulate level of the water it filters rather than the number of gallons that pass through it.
KDF has bacteriostatic properties which means that it does not support the growth of bacteria. It is not capable of killing bacteria (bactericidal).
KDF does not remove organic contaminants such as pesticides, herbicides, or volatile organic compounds (VOCs) such as trihalomethanes. It can neutralize some heavy metals but not under conditions such as exist in a shower filter where there is insufficient media and a water flow rate that is too fast to provide adequate contact time.
KDF comes in granular and filament form.