Imagine diving into the pool for another intense training session. The water is crystal-clear and clean – thanks to chlorine – but after weeks of daily laps, you notice your favourite training suit is fading and sagging. Your hair feels like straw, your skin itches, and there's that unmistakable "pool smell" clinging to you. Chlorine is both a swimmer's best friend (for keeping water sanitary) and a sneaky foe to your gear and body. In this article, we'll explore the science of what chlorine does to swimsuits, skin, and hair, and then we'll dive into how to fight back and minimise the damage. Competitive swimmers and swim families – this one's for you.
The Science of Chlorine: Friend and Foe
Chlorine is added to pools as a powerful disinfectant. When mixed with water, chlorine forms hypochlorous acid (HOCl) – essentially a mild form of bleach. This oxidative chemical kills bacteria and germs which is great for health but it's also corrosive to many materials and organic compounds. In chemical terms, chlorine oxidises substances: it breaks chemical bonds, whether in bacteria or in the fabrics and oils it contacts. Over time, this leads to wear-and-tear:
For swimsuits (fabrics)
Chlorine's oxidising action slowly eats away at fibres and dyes. It can break polymer chains and even produce hydrochloric acid in water, which further degrades materials. The result? Colours fade (as dyes are bleached) and elasticity weakens. If you've ever had a suit lose its snap or stretch out after a season, chlorine is a big culprit.
For skin and hair (organic tissue)
Chlorine can strip away natural oils and disrupt proteins. Our skin's protective oil barrier and our hair's lipid layer are chemically altered by chlorine, leaving them dry and unprotected. Chlorine can also generate irritating compounds (like chloramines) by reacting with sweat or organic matter on skin, contributing to that post-pool "chlorine smell" and sometimes causing rashes or irritation.
Chlorine is necessary for a clean pool, but understanding its chemistry helps us see why it causes dryness and damage. Think of chlorine as a necessary evil – one we can manage with the right precautions.
Chlorine vs. Your Swimsuit: Fibre Fade and Fabric Fail
Spend enough hours in a chlorinated pool, and your swimsuit will show the evidence. Competitive swimmers often find their training bathers wearing out quickly. Here's what's happening and how to mitigate it:
Fibre Degradation
Most modern swimsuits are made of blends of synthetic fibres like elastane (Lycra/spandex) for stretch and polyamide (nylon) or polyester for strength. Chlorine attacks the elastane fibres first, causing them to break and lose elasticity. A suit that once snapped back to shape may start to sag or feel loose as the elastic fibres "die" from chlorine exposure. One study[1] found that swimwear fabric lost up to 12% of its tensile strength after 200 hours in chlorinated water, and over 60% after 300 hours – essentially, after a few months of daily training, a suit can be more than half-way to falling apart!
Color Fading and Fibre Damage
Chlorine acts like a mild bleach. Vibrant suit colours may turn dull or yellowish. Microscopically, the tidy knit loops of fabric start to look disorderly and frayed as chlorine breaks filaments. In fact, researchers observed that after extensive chlorine exposure, swimsuit fibres show broken filaments and a disrupted yarn structure. The image below illustrates this: figure (a) shows a brand-new fabric with parallel, intact fibres; figure (c) shows the same fabric after heavy chlorine aging – you can see fibres pulled out and loops no longer uniform.
Microscopic view of swimwear fabric aging due to chlorine: (a) new fabric with orderly, intact fibres; (b) after moderate exposure (200 hours); (c) after heavy exposure (300 hours), many filaments broken or unraveled[1]. Chlorine's oxidative power gradually destroys the material's integrity.
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Different Fabrics, Different Fate
Not all suits are equal against chlorine. Lycra (spandex) is very comfortable and stretchy, but it breaks down fast in chlorine. In fact, a 100% Lycra suit can lose its shape in as little as 4–5 weeks of daily swimming. Polyester is much more chlorine-resistant – a 100% polyester suit can last 3–4 times longer than a Lycra one. Polyester holds colour better and doesn't degrade as quickly (though it's less stretchy). Nylon (polyamide) is somewhere in between – it offers a good balance, being more chlorine-resistant than Lycra while still providing decent flexibility. (Many competitive swimwear brands use special polyester/PBT blends that are almost "chlorine proof" for training suits.)
How to Protect Your Swimwear
You can't make a suit last forever, but you can greatly extend its life with some simple habits:
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Rinse Before and After
Always rinse your suit with fresh cool water before you swim and immediately after. If the suit is already wet with clean water, it will absorb less chlorinated water during your swim. After swimming, a thorough rinse (or gentle wash) flushes out chlorine that would otherwise sit in the fabric and continue to cause damage while the suit dries. -
Avoid Hot Water
Heat accelerates chemical reactions. Hot tubs (with chlorine) are basically a nightmare for swimsuits – the combination of high chlorine + high temperature doubles the damage. If you love hot tub soaks, consider designating an older or cheaper suit for that purpose. -
Gentle Washing and Drying
Hand-wash your suit with mild soap occasionally, or use a specialised swimsuit cleaner that neutralises chlorine. (There are "dechlorinating" swimsuit rinses available – essentially like conditioner for your suit – that can remove chlorine better than water alone.) Air dry the suit out of direct sunlight; avoid wringing it out harshly (which can stretch fibers). Sunlight also degrades fabrics over time, so drying in shade helps. -
Rotate suits
If you swim daily, give suits a day off between uses if possible. Elastics can recover a bit when not worn every single day. Owning two or three suits to rotate can prevent any one suit from getting all the exposure. -
Choose Chlorine-Resistant Suits
For training, use suits labeled "chlorine resistant." These often have no Lycra (or use special chlorine-resistant spandex) and instead use polyester or PBT yarns. They might feel tighter or less stretchy, but they'll withstand chlorine much longer. As one swimwear expert put it, "polyester swimsuits are the most chlorine resistant of all – lasting several times longer than Lycra".
No matter what, remember that once chlorine damage is done, it can't be reversed. The key is preventative care. Treat your swimsuit well, and it will return the favour with more hours in the pool before it loses its form.
Chlorine vs. Your Skin: The Itch and Irritation
Many swimmers notice that their skin feels dry, itchy, or tight after swimming. That's not your imagination – it's chlorine's handiwork:
Stripping Natural Oils
Your skin is coated with sebum (natural oils) that form a protective barrier to keep moisture in. Chlorine binds to and removes these oils, effectively cleansing your skin a little too aggressively. With the oils gone, skin can't retain moisture as well, leading to dryness and increased evaporation from the skin (what dermatologists call transepidermal water loss). The dryness can be especially problematic for people with eczema or naturally dry skin, often causing flare-ups or itching.
Irritant Dermatitis ("Chlorine Rash")
Chlorine is a chemical irritant. Some swimmers get a red, itchy rash after pool sessions, commonly called chlorine rash. It's essentially a mild form of irritant contact dermatitis – chlorine creates inflammation by disrupting the skin's barrier and this is turn prompts an immune response from the body. This is more likely if chlorine levels are high or if you're sensitive, and it can be worse on areas where a swimsuit traps chlorine against the skin.
Opening of Pores
Warm chlorinated water can open up skin pores, which allows chlorine and its byproducts to penetrate deeper. This can exacerbate the feeling of irritation or itch. Some people even notice their skin smells of chlorine for hours – that's because the chemical can lodge in the outer layers of the skin until washed off.
Other Effects
Chlorine can also irritate the eyes (ever had red, burning eyes after swimming? that's chlorine at work on the sensitive mucous membranes) and even nails (nails can become brittle with repeated chlorine exposure, since keratin proteins in nails dry out similar to hair).
How to Protect Your Skin
The goal is to minimise chlorine's contact with your skin and to restore your skin's natural moisture after swimming:
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Pre-swim Shower
Rinsing your body with fresh water before entering the pool helps – your skin will absorb some clean water, which means a bit less pool water gets in. Think of it as "filling up" your skin so it's less thirsty for chlorinated water. -
Barrier Creams or Lotions
Some swimmers use a light layer of pre-swim lotion or petroleum jelly on areas prone to dryness (like arms, legs) to act as a barrier. There are even specialty "swim lotions" that claim to protect skin from chlorine. At the very least, applying a regular waterproof sunscreen can do double duty – UV protection plus a physical barrier to chlorine on the skin. (As a bonus, sunscreen with zinc or other barriers can reduce how much chlorine contacts the skin.) -
Post-swim Shower ASAP
One of the easiest and most effective things you can get into the habit of doing is hitting the showers promptly after a swim. Showering immediately with fresh water and a gentle soap helps wash off chlorine before it causes more irritation. Use mild, moisturising cleansers rather than harsh soaps to avoid further stripping your skin. -
Use a Chlorine-Neutralising Body Wash
There are special body washes for swimmers (for example, brands like SwimSpray or TriSwim) that contain vitamin C or sodium thiosulfate, ingredients which chemically neutralise chlorine. These can be effective at removing that chlorine residue. Even a DIY approach like a quick rinse with a weak vitamin C (ascorbic acid) solution can help neutralise chlorine on the skin. -
Moisturise After Showering
This step is crucial. Within minutes of towel-drying, slather on a good moisturiser to replenish lost oils and water. Dermatologists recommend creams that contain ceramides or alpha-hydroxy acids to restore the skin barrier. Ceramides help replace the skin's natural lipids, and AHAs (like lactic acid) can draw in moisture. Regular use of a moisturiser will prevent that dry, tight feeling and keep skin supple even with frequent swims.
By following these steps – rinse, gentle cleanse, and moisturise – you can significantly reduce chlorine's drying effect on your skin. Many competitive swimmers find that with a consistent post-swim skincare routine, their skin stays healthy even with daily pool time.
Chlorine vs. Your Hair: From "Swimmer's Straw" to Healthy Locks
Hair is often the hardest hit by pool chlorine, especially for those with longer hair. Without protection, "swimmer's hair" can become a real thing – dry, brittle, tangly, and sometimes even sporting a greenish tint. Let's break down why this happens:
Loss of Hair Lipids
Healthy hair has a thin coating of natural oils (lipids) both from the scalp's sebum and from the hair's internal structures. These lipids keep hair flexible, shiny, and waterproof. Chlorine strips away and oxidises these oils. Even though lipids are a small percentage of hair's composition, they're critical for maintaining moisture and smoothness. When chlorine damages these oils, hair loses its natural lubrication and becomes more porous and dry. This is why after swimming, hair might feel like straw or get very tangled – the protective oil layer is gone.
Damage to the Cuticle
The hair's outer layer (cuticle) is made of overlapping scales of protein. Chlorine's oxidative action can lift or break these cuticle scales. A lifted cuticle makes hair feel rough and look dull. Over time, cuticle damage leads to split ends and breakage. (Chlorine isn't the only cause – mechanical forces like brushing and sun exposure also harm cuticles – but chlorine accelerates it by making the hair more fragile.)
Protein (Keratin) Damage
Inside hair, the primary component is keratin protein, held together by various chemical bonds (disulfide bonds, hydrogen bonds, etc.). Chlorine can react with these bonds. For instance, disulfide bonds (which give hair its strength) can oxidise into sulfonic acid, weakening the structure. Amino acids in the hair can be chlorinated or oxidised, leading to changes that make the hair fiber less resilient. In simple terms, chlorine can actually alter the chemical makeup of your hair's protein, especially with repeated exposure, resulting in weaker hair that can easily snap or fray.
Color Changes
If you've noticed your hair lightening or turning a funny colour during swim season, that's real. Chlorine can oxidise melanin (the pigment in hair), causing hair colour to fade or take on a different hue. Blond or light-coloured hair may even get a green tint – interestingly, that "swimmer's green" is usually from chlorine reacting with dissolved copper in the water which then binds to the hair, but chlorine facilitates it. Even without copper, chlorine alone can make both natural and dyed hair lose colour vibrancy over time [2]. And as the Tri Princeton research team noted, UV sunlight + chlorine is the worst combo – UV creates radicals that, together with chlorine, cause even more drastic colour and protein damage. (So swimming outdoors in peak sun is toughest on hair.)
Given all these effects, it's no wonder competitive swimmers often deal with dry, damaged hair. But there are ways to keep your hair in the best shape possible:
How to Protect Your Hair
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Wear a Swim Cap
They do more than just reduce drag, a snug swim cap is a swimmer's best friend for hair. It won't keep all water out, but it greatly reduces exposure by keeping hair bundled and covered. It also blocks UV on outdoor swims (remember, sun + chlorine is extra damaging). Competitive swimmers usually wear either latex or silicone caps; both are fine, though silicone caps are gentler on hair for putting on and off (latex can pull). If you really want to be kind to your hair, you can even wear a lycra cap under a silicone cap for a double layer – the lycra one isn't waterproof but adds a protective layer and makes the silicone cap easier to remove. -
Pre-wet and Pre-treat
Just like with skin, soak your hair with tap water before you swim. Wet hair will absorb less chlorinated water (hair can only hold so much water, so fill it with good water first!). Water alone will suffice for most hair types. For hair that is particularly prone to damage from chlorine, you can apply a leave-in conditioner or hair mask before putting on your cap. There are also specific "swim cap conditioners" or hair oils (like coconut oil) that create a barrier on hair strands. Some dermatologists note that a protective hair mask or conditioner can coat the hair so chlorine has a much harder time penetrating. It's worth being cautious with this piece of advice though, a swim cap won't fully prevent water from getting into it, so conditioners have the potential to rinse out and into the pool. -
Post-swim Rinse and Shampoo
Right after swimming, rinse your hair out thoroughly with non-chlorinated water. If possible, use a special swimmers' shampoo that neutralises chlorine. For example, products like TriSwim Shampoo contain vitamin C derivatives to neutralise chlorine and are formulated to moisturise hair. These shampoos and accompanying conditioners can remove the chlorine residue that would otherwise keep drying your hair out even after you leave the pool. If you don't have a special shampoo, a gentle sulfate-free shampoo plus a good conditioner is still much better than nothing – the key is to cleanse the chemicals out. -
Replenish Moisture
After washing, use a rich conditioner or hair mask to restore moisture and lipids. Look for conditioners with ingredients like aloe, vitamin E, jojoba or coconut oil, and proteins – these can help smooth the cuticle and replace some of the oils chlorine took away. You might also consider a weekly deep-conditioning treatment during heavy training periods. -
Avoid Additional Heat/Stress
Chlorine already stresses hair, so try to minimise other damage. Be careful with blow drying or straightening irons on hair that's been in chlorine; high heat on chlorine-laden hair can be extra harsh (chlorine + heat can even lighten hair further). It's better to gently towel-dry or wrap hair in a soft microfiber towel and let it air dry when you can. Also, comb out gently with a wide-tooth comb to avoid snapping brittle hair.
By implementing these steps, even high-level competitive swimmers manage to keep their hair in decent condition. It's all about consistent care – a bit of prep before, and some TLC after each swim. In the words of one hair research blog: "Loss of lipids can be remedied by using a gentle shampoo and leave-in treatment… and the key to minimising colour changes is to avoid the combination of UV light with chlorinated water – wear a swimming hat or use UV-protective products". In short, protect, rinse, and nourish. Your hair might still get dry at times, but it will be far healthier and stronger than if you did nothing.
Conclusion: Love the Swim, Outsmart the Chlorine
Chlorine is an ever-present companion for swimmers – an essential one for safety, but one that demands respect. It fades our suits, dries our skin, and fries our hair if left unchecked. The good news is that with the knowledge you've gained (and the tips we've outlined), you can dramatically reduce chlorine's wear and tear on your body and gear. Think of it as part of your training regimen: just like you cool down or stretch after a workout, you'll rinse, wash, and moisturise after the pool. These habits turn chlorine from a formidable foe into a manageable annoyance.
Competitive swimmers and swim families already pour so much dedication into the sport – a bit of extra care for swimsuits, skin, and hair is well worth it. There's nothing quite like the feeling of knowing you're doing everything you can to keep yourself in peak condition and keep your favorite swim gear intact longer. Plus, when you show up to practice with comfortable skin, healthy hair tucked under your cap, and a well-fitted suit that's not bagging out, you'll feel that much more confident and ready to perform.
So keep swimming those laps, chasing those personal bests, and enjoying the water. With a smart routine, you'll leave the pool refreshed, not wrecked by chlorine. Happy swimming, and take care!
