The sign says shower before entering the pool. Most swimmers read it as a hygiene courtesy, comply approximately by walking through a cold spray for two seconds, and think no more about it. The request is doing considerably more work than that, and the two second version does almost none of it.
Two purposes, running together
The pre swim shower is asked for on two grounds, and it is worth separating them because they lead to slightly different behaviour.
The hygiene purpose. Reducing the microbial and faecal contamination that enters water shared by other people, particularly from the perianal area. This is the purpose that people find uncomfortable to discuss and it is the reason the request specifically involves soap and specifically involves more than your shoulders. It matters most where the swimmers are small children, because the input is highest and the swimmers are least able to manage it.
The chemistry purpose. Reducing the organic and nitrogen containing material that would otherwise enter the water and consume free chlorine, generate combined chlorine and load the filtration. Sweat, skin oil, urine residue, cosmetics, moisturiser, deodorant, hair product. This is the purpose almost nobody explains on the signage, and it is the one that would change behaviour if it were explained.
A pre swim shower is not manners. It is the one water treatment step a swimmer personally performs.
What a shower that actually does the job looks like
The guidance in the code of practice from Pool Water Treatment Advisory Group and in Health and Safety Executive, HSG179 Health and safety in swimming pools is about pre swim hygiene as a system rather than a gesture. In practice, what makes the difference:
- Warm water, not a cold blast. Cold water does not remove skin oils well, and more to the point it makes people leave after two seconds. Shower temperature is an operator decision that directly determines swimmer behaviour.
- With soap, before changing into swimwear where facilities allow. Water alone does very little to oils and products. This is the single largest difference between a token shower and an effective one.
- Long enough to be a shower. Not a walk through.
- Including the areas that matter. Which for the hygiene purpose means the perianal area, and for the chemistry purpose means wherever product was applied, plus hair.
- After using the toilet, not before. Sequence matters and is free.
The gap between what the sign asks for and what people do is large, well recognised in the sector, and mostly a design problem rather than a compliance problem. A pool where the route from changing room to poolside passes through a warm shower will get a much higher rate of showering than one where the showers are down a side corridor, whatever the signs say.
Cold showers. Showers in the wrong place. No soap. No time built into a lesson schedule. Not wanting to shower in front of others. Not understanding that it is about chemistry rather than manners. Every one of those is an operator or session design issue rather than a swimmer failing, which is why this decision splits the way it does below.
Children, lessons and the twenty minute turnaround
The largest single source of pre swim contamination in a typical UK pool is a children's lesson programme, because it combines high bather density, small children, and a timetable that turns groups around quickly. It is also the setting where the pre swim shower is least likely to happen, for entirely practical reasons: the changing time is short, the children need supervision, and a shower stop adds minutes nobody has.
This is a scheduling decision, and it is one of the clearest examples on this site of a decision that looks like it belongs to a parent and does not. A parent cannot add five minutes to a lesson changeover. A swim school can. An operator can build the changing village so the route passes the showers.
Whether swimmers actually shower before a session
Owns doing it properly when it is possible: warm water, soap, long enough, after the toilet. Owns rinsing hair. Cannot create time that the timetable does not allow, cannot fix a cold shower and cannot change the layout.
Owns building it into the session. A swim teacher or coach who allocates time for showering and says why gets it. One who assumes it does not. With children, owns making it part of the routine, and owns raising it with the operator when the schedule makes it impossible.
Owns the facilities and therefore owns the outcome: shower temperature, shower number, soap provision, the layout that routes swimmers past them, the signage that explains the reason rather than issuing an instruction, and the timetable that leaves room. Owns the plant capacity for what still gets through.
Where a duty attachesPre swim hygiene provision is addressed in Health and Safety Executive, HSG179 Health and safety in swimming pools and in the code of practice from Pool Water Treatment Advisory Group. Duties on the operator as an employer and controller of premises sit under the Health and Safety at Work etc. Act 1974.
Does the pre swim shower matter differently indoors and outdoors?
Indoors it matters more, because the byproducts of the contamination you bring in do not disperse. They stay in the air of the hall and are breathed by everyone in it, including the staff who are there all day.
An indoor hall with poor pre swim hygiene and adequate ventilation may still smell. One with poor pre swim hygiene and poor ventilation reliably will.
Outdoors the chemistry effect is identical but the air consequence largely vanishes, because volatile byproducts disperse. The water still has to deal with it.
Outdoors there is also an extra input: sunscreen, applied by everybody, correctly. That is a real addition to the load and it is the right trade to make. It makes the shower more useful, not less.
The shower afterwards is a different shower
People sometimes assume that showering after swimming substitutes for showering before. It does not. They do different jobs. The one before protects the water and everyone in it. The one after is about you: rinsing treated water and its residues off skin and hair, which is ordinary care and is covered in skin after chlorine.
Both are worth doing. Neither is a substitute for the other, and if you only do one, the one before is the one that affects other people.
What a reasonable swimmer can ask for
If the showers at a pool you use regularly are cold, broken, or positioned so that nobody passes them, that is worth raising, and it is worth raising as an operational point rather than a complaint about comfort. The framing that lands is the one in this article: the pre swim shower is a load reduction step, the facilities determine whether it happens, and a hall that smells is partly a consequence of that.
Similarly, if a lesson programme leaves no time for it, the person to raise it with is the swim school or the operator running the programme, not the teacher standing in the water with eight children.
The two minute version
Shower properly before you swim. Warm water, soap, long enough to mean it, after the toilet, hair included. Do it because it reduces the material that turns into the smell everybody complains about, not because a sign asked you to. If the pool has made it difficult to do, that is a legitimate thing to tell them, because the pool owns that part.