What do the cities Los Angeles, Chicago, Phoenix, Indianapolis and Minneapolis have in common? They are the top cities with hard water in the United States! This means that the water has higher levels of dissolved minerals, usually calcium and magnesium, which can show up as a white calcium carbonate deposit. It is widely believed that hard water contributes to brittleness, breakage, and in severe cases discoloration of the cortex proteins. While the deposits are not a health concern, they can wreak havoc to your hair routine!
What does this mean for your hair?
These calcium carbonate deposits are very small, but show up as an overall dullness or even a yellow tinge in lighter colored hair. The discoloration happens when elevated levels of magnesium and calcium penetrate the cuticle and the metal ions attach to the proteins in the cortex.
This ionization will change the charge of the proteins (i.e. change the pH of the hair), attracting color deposits and causing lifting in the cuticle layers. Changes in pH allows the layers to open and close dynamically. For example, a high pH (alkaline) will cause the layers to lift and become more vulnerable to damage. The metal deposits from the hard water will create an alkaline environment and an abrasive contact that leads to discoloration, splits, tangling and increased porosity.
Calcium carbonate deposits 
No deposits
With all this in mind, how do you protect your hair from these deposits? Aside from adding a water softener filter to the water source, you can remove these deposits using a chelating agent. Chelating agents actively bind to the hard water deposits, break the bonds they would have with your hair, and allow them to fully rinse out. Most chelating shampoos are labeled as either chelating or hard water shampoos. The easiest way to identify chelating agents is looking for EDTA in the ingredients. You will often find EDTA (or a derivative) listed as one of the last ingredients in a product, meaning it is in low concentration. However, if EDTA is at the end of the ingredient list it is acting as a stabilizer and will not effectively remove hard water buildup. You want to find products with EDTA higher up on the list of ingredients to work effectively as a chelating agent for your hair.
Look for these ingredients higher in the ingredients list:
- EDTA
- Disodium EDTA
- Disodium EDTA-copper
- HEDTA
- Trisodium EDTA or HEDTA
- Tetrasodium EDTA
- TEA-EDTA
- Oxalic acid
- Potassium or sodium citrate
- Sodium oxalate
- Diisopropyl oxalate
If you have difficulty finding a product, there is an alternative method for clarifying hard water buildup is a simple Apple Cider Vinegar rinse (1 Cup water + 1-2 Tablespoons of ACV). ACV is slightly acidic, and in low concentrations can be used to lower the alkaline environment caused by hard water. This will also help loosen the bonds to let them rinse out.
References
Luqman, Muhammad Waqas, et al. “To Evaluate and Compare Changes in Baseline Strength of Hairs after Treating Them with Deionized Water and Hard Water and Its Role in Hair Breakage.” International Journal of Trichology, vol. 10, no. 3, May 2018, pp. 113–117. EBSCOhost, doi:10.4103/ijt.ijt_115_16.
Luqman, Muhammad Waqas, et al. “Effect of Topical Application of Hard Water in Weakening of Hair in Men.” JOURNAL OF THE PAKISTAN MEDICAL ASSOCIATION, vol. 66, no. 9, Sept. 2016, pp. 1132–1136. EBSCOhost, search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000386138300020&site=eds-live.
Srinivasan, Gautham, et al. “Effects of Hard Water on Hair.” International Journal of Trichology, vol. 5, no. 3, July 2013, pp. 137–139. EBSCOhost, doi:10.4103/0974-7753.125609.
Alahmmed, Lujain M., et al. “Scanning Electron Microscopy Study of Hair Shaft Changes Related to Hardness of Water.” Indian Journal of Dermatology, Venereology and Leprology, vol. 83, no. 6, Nov. 2017, p. 740. EBSCOhost, doi:10.4103/ijdvl.IJDVL_1119_16.