Swimming Pool Chlorine and Hair: Pre-Wet, Cap and Rinse Routine

The routine in one line: wet your hair with clean tap water before you get in, wear a swimming cap, and rinse and condition within an hour of getting out. Hair that’s already full of clean water soaks up less pool water, and chlorine left drying on the strand is what does most of the harm.

Summer holidays mean swimming lessons, club pools and hotel pools, and by August a lot of hair feels like straw. It isn’t your imagination. Pool water is designed to kill germs, and the very same chemistry that keeps the water safe is hard on the outer layer of every hair that sits in it for an hour, especially when that hair then dries in the sun on the drive home. The good news is that a two-minute habit before and after the swim prevents most of it, for adults and children alike. This guide is part of our Hair Care collection.

What chlorine does to your hair

Pools are kept clean with chlorine, which forms a germ-killing chemical (hypochlorous acid) in the water, and because it’s an oxidiser it reacts with whatever it touches, including the natural oils on your scalp and the protein on the surface of each hair.

Imagine each hair as a pencil wrapped in tiny overlapping scales. Chlorine strips the thin oily coat on those scales and roughens their edges. Rough scales catch on each other. Hair tangles, dulls and snaps.

One swim does very little. A season does plenty. Colour-treated, bleached and very curly hair suffers first, because their scales are already more open.

The pre-wet trick, explained simply

Hair is like a sponge. A dry sponge dropped in a bucket soaks up whatever is in the bucket, while a sponge that’s already full of clean water has much less room left for anything else, and that is the whole idea behind standing under the shower for a minute before you walk to the pool.

Adding a little conditioner or a few drops of coconut or olive oil on the lengths afterwards gives a light coating that slows how fast pool water gets in. Keep it light. Too much oil can make a cap slip and leaves an oily film in the pool, and many pools ask you to shower product off, so a thin layer on the lengths only is the polite version.

Your swim-day hair routine

1. Before: stand under the pool shower or your own tap for about a minute until hair is soaked right through.
2. Coat the lengths: a coin-sized amount of conditioner, or 3 to 4 drops of oil rubbed between the palms, over the middle and ends only.
3. Cap up: tie long hair in a low, loose bun, then pull a silicone cap on from the forehead back. Silicone keeps out more water than fabric or lycra.
4. After, straight away: rinse hair with clean water for a full minute before you do anything else, even if you’ll shampoo at home later.
5. Same day: wash with a mild shampoo and use conditioner. If you swim every day, a gentle shampoo on the lengths plus conditioner is enough; a clarifying or “swimmer’s” shampoo once a week helps lift build-up.
6. Dry kindly: blot with a towel, detangle from the ends up with a wide-tooth comb, and skip the straightener that evening.

How often to shampoo on non-swim days depends on your hair; our hair wash schedule by hair type sets out a sensible rhythm.

Why light hair turns green in the pool

Green tint shows up mostly in blonde, grey, bleached or highlighted hair. It isn’t chlorine dyeing the hair. It’s dissolved copper, from pipes, pumps or some algae-control chemicals, which chlorine helps bind to the hair’s protein. Dark hair hides it. Pale hair glows.

• Prevent it: pre-wet, cap, and rinse right away. That stops most of it.
• Lift it: a clarifying or swimmer’s shampoo made to remove minerals is the simplest option. Several gentle washes work better than one aggressive scrub.
• Skip: bleach, strong lemon juice and home chemical mixes. They dry hair further and can make the colour patchy.

If the green won’t shift after a few washes, a colourist can use a professional treatment. Minerals in home water can also dull hair; hard water and the sirka rinse covers that side.

Itchy scalp or rash after swimming?

Mild dryness and itch are common. A few other things are worth knowing:

• Irritant dryness: tight, flaky, itchy skin that fades within a day or two. Rinse sooner and moisturise.
• Hot tub rash: itchy red bumps, often under the swimsuit, a day or two after a poorly kept hot tub or warm pool. It usually settles on its own, but see a doctor if it spreads or you feel unwell.
• Allergy: true chlorine allergy is rare. Hives or swelling soon after swimming should be checked.
• Fungal infection: ringworm of the scalp can spread through shared towels and combs. Round, scaly, itchy patches with broken hairs need a doctor, especially in children.

A strong chemical smell in an indoor pool, red stinging eyes and coughing usually mean the water or air balance is off. Tell the staff and get out.

Myth: swimming often makes you lose your hair

Chlorine damages the hair you can see, making it dry and more likely to snap, but it doesn’t reach down inside the scalp to harm the roots that actually make new hair, which sit several millimetres under the skin. Swimmers who notice “hair fall” are usually seeing breakage, or shedding with a separate cause like stress, iron shortage or illness. If you find lots of full-length hairs with a tiny white bulb at the tip, the pool isn’t the likely culprit.

Swimming and hair: common questions