swimmer’s hair = damaged hair

Your hair fibers are made mainly of proteins, which are organized into two main layers. The first is the outside cuticle layer, made of overlapping scales. Healthy hair has a smooth, intact cuticle that’s covered by a protective barrier of lipids— and helps shield the inner layer of hair, or the cortex. Healthy hair with an undamaged cuticle + cortex feels smooth, strong, less tangled, and so much easier to style.

But, let’s be real—everyone’s hair has some level of damage. Different types of damage can come from multiple places in your routine. You can get mechanical damage from brushing or towel drying, heat damage from hot tools, chemical damage from salon services, and environmental damage from just living with hair. 

Damaged hair leads to negative impact on the overall structure. The cuticle scales become more spread out and porous so water can easily flow in and out of your hair. What’s in the water (and what’s getting inside your hair) can cause some extreme and unwanted reactions during your salon appointment, degrading the cortex and resulting in breakage—more on that later.

the deal with hard water 

We’ve talked about hard water before, but in case you need a refresher, hard water is high in dissolved minerals and metals, specifically calcium and magnesium. 85% of the US lives with hard water. But there are other kinds of metals present even in soft water, so chances are, you most likely have some level of metal + mineral buildup. With healthy hair, this is less of a concern as its structure is more intact and there are less places for the metals to stick to. 

But since many people do have damaged and porous hair, the hair fibers take in water more easily, and more metals + minerals along with it. Over time, this builds up on your hair cuticle and in the cortex (the middle layer of your hair) to cause unwanted chemical reactions leading to discoloration, smoking foils, and even hair disintegration. Yikes. 

the real culprit 

So, what does all of this have to do with swimmer’s hair? Well, as we said in the beginning, it’s not actually chlorine that changes the color here, but the presence of… copper. Yep, copper is the culprit. 

Copper ions can be found in the water from copper-containing algicides (a popular additive to control algae growth in pools), from metal piping, or even from the tap water source used to fill the pool. Certain forms of copper have a bright blue-green color, which, combined with the yellow undertones of bleached or blonde hair, make it appear that not so wanted green. 

But why doesn’t copper present in normal tap water turn your hair green? Contrary to popular belief, swimmer’s green is the result of your hair’s exposure to the combination of chlorine from pools and copper from the water. The chlorine acts as a strong oxidizer, enhancing copper’s absorption by your hair. So the more copper, the more green color. 

Let’s dive even deeper.