The swim cap is one of the most misunderstood pieces of swimming equipment, mostly because people expect it to do a job it was never designed for.
A cap is not waterproof
Standard silicone and latex swim caps are not seals. Water goes in around the edges immediately. Anybody who has worn one knows this and yet the expectation persists, presumably because it looks like it ought to be waterproof.
What a cap actually does:
- Reduces exchange between hair and water. Less pool water moving freely through hair, and less of whatever is in the hair moving into the pool.
- Keeps hair out of the swimmer's face, which matters for vision and therefore for safety, and matters a great deal for anybody with long hair.
- Keeps hair out of the water and out of the plant. Loose hair is a genuine operational problem for a pool: it ends up in strainers and filters and it has to be removed.
- Reduces drag, which is why competitive swimmers wear them.
- Makes a swimmer more visible, particularly a brightly coloured cap in open water, which is a real safety function that the Royal National Lifeboat Institution, water safety and open water organisers take seriously.
- Adds a little warmth, which matters in cold water where heat loss from the head is part of the picture.
A cap is a hair management device and a visibility device. It is not a raincoat for your head.
Why pools like caps
Some pools require caps and some do not, and the requirement is an operator decision. Where it exists, the reasons are usually a mixture of the plant argument above and a hygiene argument. Loose hair in a pool is caught by strainers and filters and adds to the material the plant has to handle, and hair also carries product into the water as described in what swimmers add to the water.
Rinsing hair before swimming does more on that front than a cap does, because it removes loose product before it can go anywhere. A cap plus rinsed hair is the combination that helps most.
Ordinary care for hair
Short, and the same constraint applies as elsewhere on this site. We describe everyday care and we do not make claims about hair or scalp health.
- Rinse hair with fresh water before swimming. Hair that is already wet takes up less pool water, and rinsing removes loose product.
- Wear a cap if you have long hair, for vision, for the pool and for comfort.
- Rinse thoroughly afterwards, which is the step that matters most.
- Wash and condition as you normally would. There is nothing swimming specific to add here that we are qualified to add.
Persistent itching, flaking that is not settling, sores, hair loss or anything else affecting the scalp is a matter for a pharmacist or a GP. There is a large amount of informal advice about swimmers and hair in circulation and we are not adding to it, because we have no clinical basis for any of it. For skin and scalp information the British Association of Dermatologists patient site and the NHS are the sources.
Caps, visibility and supervision
Worth pulling out because it is the function most often overlooked. A brightly coloured cap makes a swimmer visible, and visibility is the foundation of supervision. In open water this is not optional practice, it is why organised sessions issue coloured caps: it lets safety cover see who is where, and it lets a leader distinguish their group from everybody else in the water.
In a pool it matters less, but it still helps with group sessions where a teacher is tracking a specific set of children among general public swimmers.
Does the cap question change with environment?
Indoors, a cap is about hair management, plant load and comfort. Some pools require them and that is an operator decision.
The visibility function matters for lesson groups sharing a pool with the public, where a coloured cap makes a teacher's group identifiable at a glance.
Outdoors and especially in open water, the visibility function becomes a safety function. Bright caps are standard practice at organised open water sessions for exactly that reason.
A cap also covers the scalp and the parting, which is one of the areas that gets direct exposure and that nobody applies anything to. That is a genuine secondary benefit.
Whether swimmers wear caps at this session
Owns wearing one where it helps: long hair, cold water, open water, or a pool that requires it. Owns rinsing hair before and after, which does more for the hair than the cap does.
Owns the visibility decision for a group. Issuing coloured caps for an open water session is standard practice and it is the leader's call. Owns telling families in advance rather than at the water.
Owns whether caps are required at the facility, and owns the plant that has to deal with whatever gets in. Owns the pre swim shower provision that makes hair rinsing realistic.
Where a duty attachesPool operating decisions under Health and Safety Executive, HSG179 Health and safety in swimming pools and the code of practice from Pool Water Treatment Advisory Group. Open water visibility practice from the Royal National Lifeboat Institution, water safety and Swim England. Scalp and skin questions to the NHS and the British Association of Dermatologists.
Getting a cap on, which is where most of the complaints come from
Most negative feelings about swim caps come from putting them on rather than from wearing them, and particularly from putting them on children. A few practical points that solve most of it:
- Wet hair is easier than dry hair, and a wet cap is easier than a dry one.
- Caps come in sizes and children need child sizes, not an adult cap stretched.
- Silicone and latex behave differently, and people with a lot of hair generally find one of the two much easier than the other.
- Long hair goes up before the cap goes on, not after.
- Two people is easier than one for a small child, and it is worth teaching an older child to do their own rather than doing it for them at the start of every lesson.
- Fingernails are what tears caps. They are consumables and they will not last forever.
None of that is profound, and all of it removes a recurring point of friction at the start of a children's lesson, which is a supervision benefit as well as a comfort one. A teacher spending five minutes of a thirty minute lesson wrestling with caps is spending five minutes not teaching.
A word about materials
Caps are commonly made of silicone or latex, and there are people who react to latex. That is a clinical matter and not something we will characterise, other than to make the process point that matters for a session leader: if a family tells you a child cannot use latex, that is information to hold and act on, and it is not a judgement for a teacher to make or to second guess. Anyone who thinks they have reacted to something should speak to a pharmacist or a GP.
Summary
A cap will not keep your hair dry and was never going to. It manages hair, reduces what your hair puts into and takes out of the water, cuts drag, adds a little warmth and, most usefully in open water, makes you visible. Rinse your hair before and after, which does more than the cap does. And anything actually wrong with a scalp goes to a pharmacist or a GP.