A number of water companies, particularly those who do not use KDF Media®, suggest to consumers that KDF is dangerous because it adds copper and zinc to drinking water. This concern was brought up in a conversation recently and so that customer and I looked at several water samples to see if it is valid.
I compared water tests of incoming city water before treatment with tests after my Urban Defender whole house water filter, which contains 3.6 lbs of KDF Media, and/or sometimes my Kitchen Defender, which contains 1 lb of KDF Media. Flow rates in the two systems are very different. Here are those results:
City Incoming Water After Urban Defender After Kitchen Defender
Copper .057 mg/l .034 mg/l .004 mg/l
Zinc .065 mg/l .710 mg/l .510 mg/l
Copper .610 .210
Zinc .220 .020
Copper .15 ND
Zinc .008 .010
The first sample above, Detroit, shows a decrease in copper and an increase in zinc but the zinc is then decreased slightly after passing through the Kitchen Defender.
The Plano sample shows a decrease in both. Ventura show a decrease in copper and a slight increase in zinc.
Below are samples after the Urban or Kitchen Defender where there is no raw water test. Still this is interesting because as you can see the levels are either very low or ND non-detect.
It appears to me that you cannot conclude that KDF Media adds copper and zinc to the water. I don’t know what explains the ND in some case and presence in others.
Another point of interest to me is that I would suggest that both copper and zinc at these levels are beneficial and in no way harmful.