On Home Testing of Shower Filters
CuZntm TurboShower Filters are designed to remove free chlorine (CL) from water. Because of how Copper-Zinc works, OTO (orthotolodine pool testing kits that measure chlorine in water) tests do not give accurate readings. Copper and Zinc ions recombine with the chlorine molecules to produce cupric chloride and zinc chloride. Therefore, any test that measures the CI ion (such as OTO and some DPD tests) will show positive in the presence of cupric chloride and zinc chloride. The test may show positive when testing the TurboShower even though the TurboShower is working perfectly to remove the harmful chlorine. The DPD #1 Test, which tests only for CI2 is the only way to accurately measure the TurboShower’s effectiveness.
However, even DPD #1 will not accurately test chlorine’s removal from water in the presence of chloramines. Chloramine is produced when a municipality injects both chlorine and ammonia simultaneously into the water supply. This is done to reduce CI2’s ability to combine with organic matter in the water and thereby produce potentially harmful trihalomethanes (THMs). Because chloramine has less disinfecting ability than free chlorine, a higher concentration of chlorine in usually used to get the same bacteria kill rate. 1
Additionally, the presence of iodine ions in water will magnify the chloramine interference when using the OTO and DPD test methods. Also, oxidized manganese in the water may interfere with the DPD procedure. 1,2
To get accurate readings of CL2 levels, an amperometric titration method should be used because it is least likely to reflect interferences.
For practical purposes, a person’s body will tell him or her when the filtration media is exhausted and is letting chlorine through. Besides one’s nose noticing the disagreeable chlorine smell, one’s skin and hair will become dry, flaky, and itchy in the presence of chlorine.
1 Dr. Frederick A. Amalfi, PhD., Laboratory Director, Aquatic Testing and Consulting, Inc.
2 American Public Health Association, “Standard Methods for the Examination of Water and Wastewater,: 1975, 1985.