Public swimming pools across Spain are being forced to evacuate visitors after falling victim to a viral social media stunt known as the brown challenge.
In early July 2026, Spaniard Jonathan Giraldo was vacationing with his family at a public pool in Alcalá de Henares, a historic city located in central Spain, when lifeguards suddenly ordered all visitors to clear the water immediately. Giraldo and dozens of other swimmers, who were seeking relief from soaring summer temperatures, had become the latest victims of perpetrators intentionally contaminating public swimming facilities.
The online trend involves individuals ruining public recreation by defecating directly into swimming pools or secretly releasing human feces brought from home in plastic bags. Participants record their actions on video and upload the footage to TikTok, the short-form video platform operated by ByteDance, as well as other social networks.
Spain has faced recurring summer heatwaves with orange alert warnings, making municipal pools a crucial public service for residents trying to cool down. However, the intentional contamination of these waters has repeatedly disrupted public operations during peak summer heat.
Rising pool closures across Spanish municipalities
The trend first swept across Spain in 2018 and has since affected approximately 300 public pools nationwide, according to reports in local media. The phenomenon has surged in popularity during 2026, leaving visitors, lifeguards, and municipal leaders shocked by the ongoing disruptions.
Pedro Parrales, technical director of the National School of Aquatic Rescue, stated that lifeguards already receive low pay and should not have to deal with individuals relieving themselves in public swimming pools.
Local administrative authorities expressed deep frustration over the difficulty of catching perpetrators. Municipal officials noted that identifying those responsible is extremely hard because authorities cannot install surveillance cameras inside pool facilities or require personal identification from every visitor at the entrance.
Restoring a contaminated pool requires an extensive sanitation process that extends far beyond a few hours of routine cleaning. Under official health regulations, facility managers must execute thorough hyperchlorination of the water and collect chemical samples for laboratory verification.
Manuel Alonso, the sports councillor in Zamora, a city in northwestern Spain near the Portuguese border, explained that laboratory test results are never immediate. Alonso stated that it takes between 24 and 48 hours to receive testing results and determine whether a swimming pool can safely reopen to the public.
In cases where high concentrations of bacteria are detected, water treatment systems must be completely drained. This procedure results in the loss of thousands of litres of treated water, creating severe operational problems during official drought warnings.
Sanitation delays and public health hazards
Medical professionals warn that fecal contamination poses serious health hazards to swimmers. Karina Kinyasheva, a doctor of clinical laboratory diagnostics at the medical firm LabQuest, warned that fecal matter introduced into swimming pools can spread dangerous intestinal pathogens.
Kinyasheva highlighted risks from noroviruses, rotaviruses, enteroviruses, Salmonella, and pathogenic species of Escherichia coli. She emphasized that young children, elderly individuals, and people with chronic health conditions face the highest risk because they suffer more severe complications from gastrointestinal infections.
Kinyasheva noted that chlorine in pool water does not instantly disinfect contaminated water. Pathogens react to chlorine at different rates, with certain bacteria and viruses surviving for extended periods despite chemical treatment.
For individuals present in a pool during a contamination incident, Kinyasheva recommended showering immediately and washing the face with clean water. She clarified that swimming in contaminated water does not mean a person will automatically fall ill, but anyone experiencing nausea, vomiting, diarrhea, abdominal pain, fever, or severe weakness in the subsequent hours or days should consult a doctor.
Medical and psychological perspectives on pool pranks
Healthcare workers directly treating affected patients take a stern view of the trend. Lorenzo Armenteros, a local family doctor, described individuals who defecate in public pools as unconscious of their actions, questioned their intelligence, and suggested the presence of psychiatric pathologies.
Armenteros characterized the trend not merely as irresponsible behavior, but as a deliberate crime against public health. He also dismissed claims that feces might enter pools accidentally due to sudden illness, explaining that an urgent medical need for bowel movement would produce liquid rather than solid feces, confirming that the contamination is intentional.
Psychologist Rodion Chepalov explained that perpetrators are motivated by more than just collecting social media likes. Chepalov stated that individuals discover a cheap way to feel personal influence over others, as a few seconds of disgusting behavior leads to immediate pool closures, forced evacuations of dozens of people, and demanding cleanup work for facility staff.
According to Chepalov, this creates an illusion of power where an individual feels that despite being nobody, a single act can force everyone else to alter their plans. He added that defecation represents one of the strongest cultural taboos, and publicly violating it demonstrates a refusal to obey societal rules through a mix of aggression, shock tactics, and infantile pleasure.
Chepalov noted that outrageous behavior provides a shortcut to rapid online attention, whereas positive actions like helping elderly people generate minimal news coverage. He explained that human brain architecture features a negative bias that quickly notices dangerous or abnormal behavior. This leads to emotional contagion as users forward videos to friends, creating a paradox where public outrage rewards the perpetrator with the social validation they sought.
Risks of pool urination and environmental impacts
In addition to fecal contamination, medical experts warn against urinating in swimming pools and open bodies of water. Urologist Neil Parekh warned that urinating in pools is harmful because urine reacts with chlorine, reducing the amount of free chlorine available to neutralize microbes.
Parekh explained that this reaction creates chemical irritants called chloramines, which cause eye redness, skin irritation, and respiratory problems, particularly for individuals with asthma. Survey data indicates the practice is widespread, with 27 percent of respondents admitting to having urinated in a swimming pool at least once.
Gynecologist Tatiana Ilyukhina advised against urinating in natural bodies of water such as lakes and ponds. She explained that completing urination creates a vacuum effect in the urethra that can draw surrounding water back into the body.
Ilyukhina noted that this vacuum effect allows pathogens to enter the urinary tract, potentially causing urethritis, cystitis, and pyelonephritis. She stressed that women face higher risks due to having a shorter and wider urethra, while detergents and industrial pollutants in natural water bodies can trigger severe inflammation.
In open ocean environments, Andrew J. Esbaugh, a professor at the University of Texas at Austin Institute of Marine Science, noted that human urination can provide ecological benefits. Esbaugh explained that urine contains urea, which helps the body eliminate excess nitrogen. When nitrogen mixes with ocean water, it forms ammonium, a compound that feeds marine vegetation like algae and supports the oceanic life cycle.
However, Esbaugh warned that urinating in enclosed bodies of water promotes excessive algae growth and microorganism expansion, disrupting local ecosystems. He also dismissed the widespread belief that human urine attracts sharks. Researchers at National Geographic tested the theory by placing two divers in the ocean, one slowly releasing urine from a bottle while the other remained inactive. Monitoring shark brain activity revealed no reaction whatsoever, proving the belief to be a myth.
