Chlorine doesn't actually turn hair green. Copper does: tiny amounts of copper dissolved in pool water bind to your hair, and chlorine makes that easier by roughing up the hair first. So if your blonde ends have gone a little swampy after a few weeks of lane swimming, you haven't done anything wrong. It's chemistry, and once you know how it works, it's much easier to work around.
For the bigger picture on what pool water does to your hair, see our guide Is Swimming Bad for Your Hair?.
What actually turns hair green in the pool?
Copper, not chlorine. Copper ions in the water are absorbed by the hair and bond with its keratin, forming a copper and keratin complex that gives off the greenish tint. Dermatologists say the same thing in plainer words: it's the minerals in pool water, not the chlorine, that leave the green behind.
Doctors even have a name for it. A 2024 case report calls it chlorotrichosis: copper building up in light-coloured hair that was already damaged. Think of a white T-shirt slowly picking up a tint from being washed with jeans.
Where does the copper in pool water come from?
Mostly from the products used to keep the water clear, and sometimes from the pipes. Pools may add copper sulfate to stop algae from growing, at around 0.5 parts per million, and copper can also get into the water when pipes corrode.
And it isn't always the pool. Green hair has also been linked to copper in tap water, usually from corroding copper pipes. So if you see green without swimming, ask a plumber about the pipes.
Whichever pool you swim in, your bag probably already holds a cap, goggles, a towel and a small army of bottles (our swim bag essentials list has the full rundown). If one has ever leaked onto your clean clothes, you'll see why some swimmers switch to a solid bar.
Shampoo, body and face wash, all in one bar. Cooling, refreshing and designed for those always on the go.
One solid bar for hair, body and face means nothing to leak in your bag. It won't do anything about copper, though, so back to what does.
So what does chlorine have to do with it?
Chlorine is the accomplice, not the culprit. Chlorine oxidises hair, damaging it and making it easier for copper to get in. In a 1978 study, hair exposed to water with copper but no chlorine still turned green.
Think of chlorine as the one who opens the door and copper as the guest who walks in. That's also why the tint shows up after frequent swims: think weeks of 7am lane sessions, not one splash on a Saturday. Which brings us to whose hair is most at risk.
Why does it show up on blonde, bleached or highlighted hair?
Because the green is easiest to see on light hair, and damaged hair grabs copper more easily. The effect happens to everyone but is much less visible on dark hair, and bleached, straightened or sun-exposed hair is the most susceptible, because its internal bonds are already broken.
A 1995 paper describes the same pattern: prior damage from bleaching, dyeing or the sun, plus frequent contact with chlorinated water, makes green hair more likely.
Fresh highlights and a busy swim week? See our guide on swimming with coloured hair or highlights.
How can you stop your hair going green?
Keep the pool water out, or keep it from sticking. Here's what the sources suggest:
- Wear a swim cap. It's the simplest physical barrier, and it helps especially if you swim often or colour your hair.
- Wet your hair with clean water first. Hair that's already full of fresh water can absorb less chlorinated water.
- Add a layer of conditioner or oil. Dermatologists suggest a leave-in conditioner or hair oil before you swim. The doctors in the 2024 case report also recommended conditioner before swimming.
- Pre-wash with an alkaline shampoo. One of the sources also mentions pre-treating hair with an alkaline shampoo before you swim.
- Rinse straight after. Rinse with fresh water as soon as you get out, then wash with a gentle shampoo and conditioner.
How often should you wash? See do you need to wash your hair after every swim? Using a bar? Here's whether you need conditioner with a shampoo bar.
How do you get the green out again?
With a shampoo made to lift metals. The recommended ones are so-called chlorine removal shampoos that contain EDTA, an ingredient that binds to metal ions. Our guide on which shampoo to use if you swim a lot explains what's in them. In the 2024 case report, an EDTA shampoo led to a clear improvement within 8 weeks.
Doctors have also used stronger options, such as hydrogen peroxide. Those are for a hairdresser or dermatologist to decide with you, not a kitchen experiment the night before a wedding.
Meanwhile, if your pool locker looks like a pharmacy shelf, with shampoo, conditioner and body wash fighting for space, swapping two of them for one bar is a small win.
Shampoo, body and face wash, all in one bar. Keep your hair and skin healthy on the go. Monoï-infused scent with a touch of vanilla. Designed for those always on the go.
Whatever you wash with, the cap and the fresh-water rinse do the heavy lifting for green hair. Which leaves the internet's favourite remedies.
Which green hair fixes are myths?
Mostly the ones involving your kitchen. Here's how the popular claims compare with what the sources actually say:
| Claim | What the sources say |
|---|---|
| "Chlorine turns hair green." | Copper does. Chlorine damages hair so copper binds more easily. |
| "Only blondes get it." | It happens on all hair but is far less visible on dark hair. |
| "Ketchup or tomato sauce gets it out." | There's no scientific evidence for tomato sauce remedies. |
| "It's permanent." | In one reported case it clearly improved within 8 weeks of using an EDTA shampoo. |
| "A cap is pointless." | A cap is a recommended physical barrier. |
Swimming on holiday? A solid bar isn't a liquid, so it stays out of your liquids bag at airport security. Our guide to taking soap on a plane covers the rules.
Shampoo, body and face wash, all in one bar. Cooling, refreshing and designed for those always on the go.
Back home, the routine stays the same. For chlorine, salt water and sun together, see saltwater, chlorine and sun for daily swimmers.
Summary
Green pool hair comes from copper, not chlorine. Copper from algae treatments or corroding pipes binds to your hair, and chlorine makes that easier by damaging the hair first. Light, bleached and highlighted hair shows it most.
A swim cap, a fresh-water rinse before you get in, a layer of conditioner and a wash afterwards are the main things that help. If you've already gone green, a shampoo containing EDTA is the fix the sources point to, and a hairdresser or dermatologist can help if it doesn't shift.
Frequently asked questions
Why does chlorine turn hair green?
It doesn't on its own. Copper in pool water binds to the keratin in your hair and causes the green tint. Chlorine plays a supporting role by damaging the hair so copper gets in more easily.
Why is there copper in swimming pool water?
Mostly because of the products used to keep the water clear: pools may add copper sulfate to stop algae from growing. Copper can also get into the water when pipes corrode.
Why does blonde hair turn green in the pool?
Because the green is easiest to see on light hair, and damaged hair grabs copper more easily. Bleached, straightened or sun-exposed hair is the most susceptible, because its internal bonds are already broken.
Can brown or black hair turn green in the pool?
It happens to everyone, but it's much less visible on dark hair.
Can my shower at home turn my hair green?
It can. Green hair has been linked to copper in tap water as well as pools, usually caused by corroding copper pipes. If you see green without swimming, ask a plumber or your landlord to look into it.
Does a swim cap stop green hair?
A cap is the main physical barrier the sources recommend. No method blocks chlorine completely, though, so combining a cap with a fresh-water rinse and conditioner works best.
Does wetting your hair before swimming help?
It can. Hair that's already full of fresh water can absorb less chlorinated water.
What shampoo gets green out of hair?
A so-called chlorine removal shampoo that contains EDTA, an ingredient that binds to metal ions. If the green doesn't shift, a hairdresser or dermatologist can help.
How long does it take to get green out of hair?
It varies. In one case reported in 2024, an EDTA shampoo led to a clear improvement within 8 weeks. If it doesn't shift, or your hair is coloured, ask your hairdresser or a dermatologist.
Does ketchup get green out of hair?
There's no scientific evidence for tomato sauce remedies. A shampoo containing EDTA is the fix the sources point to.
Sources
The facts in this article are based on the sources below, checked in October 2026.
- Why does my hair turn green from the swimming pool? Magdalena Wajrak, The Conversation, 2023.
- How To Protect Your Hair From Chlorine. Cleveland Clinic, 2026.
- The Greening of Hair: A Unique Case of Chlorotrichosis and Its Management. Lomelí-Legaspi E. et al., Skin Appendage Disorders, 2024.
- Cupric Keratosis: Green Seborrheic Keratoses Secondary to External Copper Exposure. Peterson J. et al., Cutis, 2006.
- Green hair. Cutis, 1995 (abstract on PubMed).
