Research & Data

Pools

  • One out of every 2 pools is improperly chlorinated, filtered, or managed according to the CDC.
  • The CDC found evidence of E. Coli (the leading cause of UTIs) in 58% of swimming pool samples, indicating that pools contain this harmful bacteria more often than not.
  • A 2019 survey by the Water Quality & Health Council found that 51% of American adults use pools as a substitute for showers or baths (like taking a dip after a workout or sauna session), with 48% admitting they never shower before swimming, 40% acknowledging they urinate in pools, and 24% stating they would swim within an hour of having diarrhea, and most people did not know that pool chemistry can be affected by personal care items such as makeup and deodorant.

 

UTIs

  • UTIs are the most common bacterial infections globally, with uropathogenic Escherichia coli (UPEC) responsible for approximately 75% of cases; in the United States alone, UTIs account for over 10 million outpatient visits, more than 2 million emergency department visits, and 100,000 hospitalizations annually (Zagaglia et al., 2022). Further, UTIs are the second most common type of infection in the world (Graham et al., 2021).
  • A Finnish study (Patjas et al., 2024) found that swimming in natural waters (within the past two weeks) was associated with a 3.4-fold increased odds (≈240% higher odds) of having a UTI compared to individuals without UTI. (As similarly confirmed by Søraas et al., 2013.)
  • A Belgian study (Van Gerwen et al., 2016) found that women who regularly swim in chlorinated pools have a higher incidence of vulvovaginal irritation, imbalance, and recurring bacterial vaginosis (BV).
  • An American study (University of California, Berkeley, 2022) found that swimming in E. coli contaminated ocean  water can increase UTI risk.
  • Altered perineal microbiomes, influenced by factors such as swimming and bubble-bath water exposure, may increase the risk of vulvovaginitis and urinary tract infections in preadolescent girls (Gorbachinsky et al., 2014).
  • The Urology Care Foundation (powered by the American Urological Association) states a clear correlation between swimming and UTIs. 

 

Vaginal Microbiome

  • A study on the vaginal microbiome by Seed found that “90% of women have an unstable vaginal microbiome when stability is defined as being in an optimal microbiome state (CST I, dominated by Lactobacillus crispatus) for 90% of the time or more”

 

Hormonal Disruption

  • Disinfection byproducts formed when chlorine reacts with organic matter, such as trihalomethanes and haloacetic acids, have been shown to exhibit endocrine-disrupting activity in animal models, interfering with hormone receptors and potentially affecting hormonal systems (Liu et al., 2023; Zhang et al., 2022).

Vulvitis

  • A study published in the Canadian Urological Association Journal discusses how certain pools or baths may increase the colonization of bacteria and the occurrence of vaginitis, potentially leading to UTIs in young girls.

pH Disruption

  • Chlorine, being alkaline with a pH ranging from 7.2 to 7.8, can alter the natural acidic pH of the vagina, which typically ranges from 3.8 to 4.5.
  • Exposure to chlorinated pool water (with a pH ranging from 7.2 to 7.8) can disrupt the vaginal environment by raising the normally acidic pH (which typically ranges from 3.8 to 4.5) and potentially affecting the protective Lactobacillus population, increasing the risk of irritation or infections. Similarly, ocean water, with a pH around 8.1, can dry or irritate sensitive skin (resulting in vaginitis). 

BV

  • BV is associated with a rise in vaginal pH above 4.5 and a decrease in Lactobacillus species (Schwebke, Muzny & Josey, 2014)

Yeast Infections

  • Vaginal dysbiosis—characterized by decreased Lactobacillus species and increased microbial diversity—is linked to an increased risk of yeast infections. This imbalance can compromise the vaginal mucosal barrier and immune responses, promoting the growth of opportunistic pathogens like C. albicans .

Bladder Cancer

  • Researchers examined lifetime water-related habits and exposure to the disinfection byproduct trihalomethanes among 1,219 people with bladder cancer and 1,271 controls. A comparison between the groups indicated that swimming in pools with the chemical was associated with an increased risk of bladder cancer.

Other Evident Conclusions:

  • Chlorine, a powerful disinfectant, can alter the human microbiome by killing beneficial strains, thus allowing harmful or opportunistic strains to overgrow. Chlorine is known to alter the skin microbiome (Puce et al., 2022) and, when ingested,  the gut microbiome, but there is insufficient research into how it specifically impacts the vaginal microbiome.
  • Ocean water has been found to disrupt the skin microbiome as well by removing resident  skin bacteria while introducing new, ocean-derived microbial species (Nielsen et al., 2019). Naturally, it could be suggested that the same would occur in the vaginal region.
  • The vaginal wall is highly absorbent due to its mucosal, porous nature and is richly vascularized, providing a direct route into the bloodstream. Given these characteristics, it is a logical deduction that substances like chlorine could be readily absorbed through this tissue and distributed systemically (potentially leading to endocrine disruption).