Swimming in Denmark: Chemicals, Cultural Norms, and the Politics of Pool Hygiene
A swimming pool is never just water. It’s a heavily managed aquatic ecosystem, held in precarious balance by chemistry, cultural norms, and care. Without treatment, pools explode with algae, bacteria, protozoa, and fungi, not to mention insects. Chlorination, the standard treatment worldwide, reshapes that multispecies world: it kills off some life forms while allowing chlorine-resistant ones to persist, reorganizing microbial relations and subtly altering swimmers’ own microbiomes.
I love being in the water. My friend Ingrid teases that it’s my happy place because I grew up near the coast. Whatever the reason, I try to swim wherever I travel. This summer that meant laps in Copenhagen, Hamburg, and Amsterdam. Traveling this way turns swimming into a kind of ethnographic practice. Each pool is not just a recreational site but a multispecies world, with its own norms, infrastructures, and microbial politics. The water may look the same, but what counts as “clean,” “safe,” or “pleasant” varies remarkably from place to place.
Denmark’s Lesson
Of all the places I have swum, Denmark stands out. In Copenhagen, I frequented a public pool in a working-class part of town. Nothing fancy, just a neighborhood facility paid for by the municipal government (Københavns Kommune). Entry was free, the facilities were as nice as the modest private club I pay to swim at in Nashville, and the water quality felt remarkable.
It took a few weeks of daily visits to learn the Danish pool rules and norms. No cell phones for privacy reasons, but with the spillover benefit that no one was scrolling by the pool. No shoes are allowed beyond the entrance—they are taken off and placed on a rack. One should bring (not wear) a clean bathing suit. But most striking are the strict norms around showering. Upon entering the changing room, signs (see Figure 1) instruct swimmers to shower completely and naked, using soap and shampoo, paying particular attention to those regions where bacteria collect: hair, underarms, genitals, buttocks, and feet. Sunscreen and perfume should not be reapplied after showering. My linguist partner Mareike pointed out something I might have missed: the Danish word on the sign (husk, “remember”) frames hygiene not so much as a command but more as a collective understanding. There is no formal policing, but staff circulate and older men gently enforce the rules. A shy teenager who tries to shower in swimming trunks will be told to take them off. Only after a thorough wash do you put on your clean bathing suit.
The logic is simple: if you wore your swimming trunks into the shower, all your genital bacteria would be transferred onto the suit and then into the pool. By insisting on thorough soapy washing, the Danes reduce the microbial load before anyone touches the water. The result is noticeable. The pool water was only lightly chlorinated—perhaps 1-2 parts per million, about half that of my pool in Nashville. It felt pleasant, I could swim with my eyes open, and I could not taste the sunscreen and perfume that normally plagues my swims.
This system seemed better not only for swimmers’ comfort but also for our bodies. With the microbial load reduced upstream, swimmers absorb less chlorine and inhale fewer disinfectant by-products. The Bavnehøj Friluftsbad in Copenhagen exemplifies an approach to microbial management based not on chemical domination but on cultural norms and social enforcement. Denmark, I concluded, has much to teach us, and not just about swimming but about provisioning health and wellbeing more broadly.
Chlorine as Purification Fantasy
What I experienced in Copenhagen contrasts with Hamburg, Amsterdam, and Nashville, where pools rely on heavier chlorination. Unlike most outdoor pools in the U.S., those in Germany and the Netherlands require one to shower before entering, but this is usually a perfunctory washing with bathing suits on. I always thought the Germany and Dutch pools must be really clean, but that was before I swam in Denmark.
To understand what is at stake, it helps to recall Bruno Latour’s (1993) insight that modernity rests on an illusion of purification, the attempt to separate nature from culture, human from nonhuman. Chlorinated pools are a microcosm of modern hygienic modernity: the fantasy of a human-only space carved out of messy microbial ecologies. Yet such modernist purification is a categorization scheme, not the way the world actually emerges. Pools are hybrid assemblages of the human and nonhuman, the biological and chemical: chlorine-resistant organisms persist; human secretions produce chemical reactions in contact with chlorine; hair, sunscreen, and skin cells circulate in the water.
Hypochlorous acid forms when chlorine dissolves in water. It penetrates cell walls and disrupts microbial enzymes and DNA, effectively eliminating bacteria like E. coli, viruses including norovirus, and parasites such as Giardia. Chlorine also reacts with organic matter (such as sweat and urine) to form haloacetic acids and chloramines, the volatile compounds that give pools their familiar chlorine smell. (For swimmers, it is best not to dwell on the source of the odor.) These compounds cause minor eye and skin irritation, but they can also trigger respiratory problems and have been associated with bladder and reproductive health risks (Goodman and Hays 2008; Richardson 2021).
Michelle Murphy (2017) reminds us that molecules are not isolated abstractions. Chlorine is not just “Cl” in a table but an agent enmeshed into infrastructures, inequalities, and bodies. Deployed as a universal disinfectant, chlorine volatilizes in the air, concentrates in pools, travels downstream in wastewater. Bathers absorb chlorinated water through the skin, mucous membranes, and inhalation. This changes microbiomes — not only killing pathogens but also reshaping skin flora and possibly gut microbiota via ingestion.
Chlorine does not just kill; it sets the conditions of possibility in which lifeforms thrive. It keeps E. coli and Cryptosporidium at bay, while allowing chlorine-resistant microbes to survive (e.g., Pseudomonas aeruginosa, Legionella in biofilms). It reorganizes relations among species, bodies, and infrastructures. Donna Haraway (2008) might call this a form of disciplined companionship: chlorine deciding which microbes we tolerate, which we eradicate, and how we coexist in chemical intimacy.
Nicholas Shapiro (2015) uses the term chemosphere for the clouds of industrial chemistry in which we live. Pools, in that sense, are microcosms of a broader condition. Chlorine circulates through pumps and bodies, connecting municipal budgets to petrochemical supply chains, and human leisure to chemical warfare on microbes. The pool is a chemosocial assemblage—at once recreational, regulatory, and respiratory.
Public pools are intensely managed spaces. Lifeguards dip test strips to check compliance with World Health Organization and CDC standards. The pH and chlorine levels are logged, regulated, and enforced. These routines embody a sort of microbiopolitics (Paxson 2012): the governance of human–microbe relations through norms and technologies.
The Danish example reveals a different calculus. Rather than relying on chemical overkill to sanitize after the fact, it minimizes microbial input by making hygiene an expression of shared trust and embodied cooperation.
Conclusion
Swimming pools reveal much about how societies imagine health, hygiene, and community. Chlorination is not just about disinfection; it is about how we live with microbes. Yet, swimming pools also perpetuate the fantasy of water as a human-only medium, cleansed of microbial life.
For anthropologists and public health practitioners, pools offer a productive site for thinking through the politics of prevention versus treatment, individual versus collective responsibility, and chemical versus cultural solutions to health challenges. The Danish model offers more than a technical alternative to heavy chlorination; it is a different mode of management that emphasizes cooperation over domination. Rather than fighting microbes in the water with chemical warfare, Denmark prevents their introduction in the first place through collective action. The water thus becomes a medium of shared responsibility, not simply a chemically patrolled frontier.
The lessons extend beyond swimming pools to broader questions about how we design public health interventions. Too often, we reach for technological fixes (filters, disinfectants, antibiotics) when cultural coordination might achieve the same ends with fewer side effects. The Danish pool model suggests that sometimes the most sophisticated solution is the most social one: embedding health practices in collective norms rather than individual compliance with chemical systems.
References
Goodman, Michael and Sean Hays. 2008. “Asthma and Swimming: A Meta-Analysis.” Journal of Asthma 45(8): 639-647.
Haraway, Donna. 2008. When Species Meet. Minneapolis: University of Minnesota Press.
Latour, Bruno. 1993. We Have Never Been Modern. Cambridge: Harvard University Press.
Murphy, Michelle. 2017. “Alterlife and Decolonial Chemical Relations.” Cultural Anthropology 32(4): 494–503.
Paxson, Heather. 2012. The Life of Cheese: Crafting Food and Value in America. Berkeley: University of California Press.
Richardson, Susan D. 2021. “Tackling unknown disinfection by-products: Lessons learned.” Journal of Hazardous Materials Letters 2: 100041.
Shapiro, Nicholas. 2015. “Attuning to the Chemosphere: Domestic Formaldehyde, Bodily Reasoning, and the Chemical Sublime.” Cultural Anthropology 30(3): 368–393.
World Health Organization. 2006. Guidelines for Safe Recreational Water Environments, Volume 2: Swimming Pools and Similar Environments. Geneva: WHO.