In short
It can. On skin washed with hard water, more foaming agent stays behind and irritates it. Softening the water reduced the effect. Rinse the lather off thoroughly with plenty of water.
What did the study find?
In a study in England with 80 people, skin was washed with water of different hardness and the same foaming agent (SLS). Areas washed with hard water had significantly more foaming agent residue. This residue increased the skin's water loss and caused irritation. With a water softener, this negative effect was reduced.
The same study saw no clear effect from the chlorine in the water.
Why does it happen?
Calcium and magnesium, which make water hard, can combine with the foaming agent to form a layer that stays on the skin. Rinsing doesn't fully remove this layer, and it keeps irritating the skin.
What can you do at home?
Rinse off the lather with plenty of water, without rushing. Choose a cleanser without harsh foaming agents. If your water is very hard, you might consider a shower filter or a home water softening system. If your skin feels tight after showering, apply a moisturiser.
Sources
- Danby SG et al. (2018). The Effect of Water Hardness on Surfactant Deposition after Washing and Subsequent Skin Irritation. Journal of Investigative Dermatology 138(1):68–77. doi:10.1016/j.jid.2017.08.037
- Walters RM et al. (2012). Cleansing Formulations That Respect Skin Barrier Integrity. Dermatology Research and Practice 2012:495917. doi:10.1155/2012/495917
These studies were not carried out with EcoProbiotic products.