Swimming is a chemistry problem and a duty of care problem.
Most publishing about sun and swimming assumes one adult on a beach making one decision. Swimming is rarely that. It happens in treated water somebody else doses, in shared facilities somebody else runs, during sessions somebody else leads, and very often it involves children. So this site asks a different question on every page: who owns this decision.
Every page splits the decision, and every page splits the environment.
Two blocks appear throughout. The first names a decision and says who owns it, because in swimming the answer is often not the person in the water. The second splits the answer by environment, because almost nothing on this subject has one answer for an indoor hall and an outdoor lido.
Who owns this
One decision, split three ways between the swimmer, the session leader and the facility operator, with the guidance or instrument named where a duty actually attaches. It is the real shape of the problem in a supervised environment.
Indoors or outdoors
The same question answered twice. Indoors, ultraviolet is essentially not the issue and the problem becomes air and water. Outdoors it is the issue, and it compounds with reflection, dwell time and very little clothing.
Numbers and names
No chemical concentrations, no dosing values, no water parameter figures, no named pool, club or facility, and no prices. Those belong to the operator and the current guidance, and we point at both rather than reprinting either.
Six sections, one question running through all of them.
Pool water
What the water in a pool actually is, and why calling it chlorine explains nothing
6 articles02Indoors
Indoors, ultraviolet is essentially not the issue, and that changes the whole question
5 articles03Outdoors and lidos
Open air pools, lidos and the exposure picture nobody plans for
5 articles04Open water
Cold, wind, glare and water you did not treat
6 articles05Duty of care
Most swimming happens under somebody else's supervision. Somebody owns each decision.
8 articles06Afterwards
Skin, hair, eyes and shared facilities, described as everyday care and never as treatment
5 articlesNo product recommendations. No affiliate links. No ranked lists.
We do not tell you which sunscreen to buy, we take no commission on anything, and we publish no league table of pools, clubs or providers. There is a paid register, it is alphabetical, every entry is marked as paid, and a listing is not a safety endorsement because we have inspected nowhere. The criteria, the rates and the list of things money cannot buy are all published.
Where to start.
What pool water actually is, and why calling it chlorine explains nothing
Treated pool water is a managed system of circulation, filtration, disinfection and pH control, not a tank of chlorine. What each part does and who holds it.
ReadPool waterCombined chlorine and chloramines: why the smell means the opposite of what people assume
The swimming pool smell is not chlorine doing its job. It is chloramines, formed when disinfectant reacts with what swimmers bring in. What that tells you and who can fix it.
ReadPool waterWhat swimmers add to the water: sunscreen, cosmetics and the chemical load
Sunscreen, moisturiser, hair product, deodorant and make up all enter the water with the swimmer. What that does to a treatment system, and how to handle it without giving up sun protection.
ReadPool waterWhy pools ask you to shower first: hygiene, chemistry, or both
The pre swim shower is a chemical intervention as much as a courtesy. What it actually removes, why it changes the water, and why so few swimmers do it properly.
ReadPool waterWho actually treats the water, and what qualification sits behind it
Pool water is dosed, tested and adjusted by named people with specific training. Who they are, what a pool plant operator qualification is, and where the legal duty sits.
ReadPool waterWhat gets tested, how often, and what a swimmer can reasonably ask to see
Pool water is tested repeatedly through the day and recorded. What the tests are for in structural terms, what the records exist to prove, and what a swimmer can ask.
ReadIndoorsIndoor pools and ultraviolet: why the sun question mostly disappears
Ordinary building materials stop the ultraviolet that matters, so an indoor pool is not a sun exposure environment. What that does to the whole product question indoors.
ReadIndoorsShould you wear sunscreen at an indoor pool
There is no ultraviolet exposure to protect against indoors, and the product adds load to the water. The straightforward answer, and the edge cases where it changes.
ReadIndoorsIndoor pool air, ventilation and why the hall smells
The indoor environmental problem is air, not sun. What accumulates above the water, why ventilation is the control, and who owns it.
ReadThe Swimming SPF briefing
A monthly email for swimmers and for the people who run sessions. One subject at a time, worked through properly. It carries a single sponsor line, always labelled, sold at a published rate, and the sponsor sees nothing before you do and changes nothing.
We use your address for the briefing and nothing else. See privacy.