It's the last thing anyone wants to think about when they're swimming in the ocean, but the contamination of raw sewage in sea waters is becoming what one researcher has called "an increasingly critical issue for public health."

What's happening?

A February publication in the journal Microbiology, authored by Jonathan Cox of Aston University, provided an overview of the types and degrees of coastal water contamination from sewage, with a focus on the United Kingdom.

Cox explained that several types of pathogenic bacteria are commonly found in such sources. These bacteria — including multiple strains of Vibrio, Chlamydia, E. Coli, Streptococci, and more — pose a "significant" risk to human health and the environment.

Why is this concerning?

Ingestion and inhalation of sewage-contaminated water have led to outbreaks of gastroenteritis and bacterial pneumonia. Exposure can also cause skin infections, ear and eye infections, and tonsillitis. As is the case with most public health threats, at-risk populations — much older, much younger, immunocompromised, and pregnant people — can be especially susceptible to serious illness.

Aside from these human health concerns, the pathogens can endanger the balance and safety of entire coastal ecosystems. For example, the presence of sewage can cause algal blooms, which in turn can choke out resources like light and oxygen from reaching beneficial native plants and animals.

And because shellfish serve as filter feeders — eating up organic matter or smaller organisms found in water — the bacteria can often accumulate within them. In fact, some people have developed severe food poisoning from affected shellfish. 

In grave cases, food poisoning can be fatal, but there are additional risks. The more this bacteria re-circulates in the food chain and food supply, and the more people are treated for the illness it causes, Cox warns, the more antimicrobial resistance may build, bringing weighty consequences.

The World Health Organization estimated that bacterial antimicrobial resistance "was directly responsible for 1.27 million global deaths in 2019." 

Diarrheal disease, like gastroenteritis, is also a leading cause of mortality in children globally, driven largely by contaminated water and disproportionately impacting low- and middle-income countries. There, access to clean drinking water is often already compromised due to lack of infrastructure, ongoing conflict, drought, and more.

What can be done?

Cox explains in the paper that while monitoring efforts and strict discharge standards are in place for sewage treatment plants, they may not be enough. "Storm overflows were intended to release surplus sewage into the sea on rare occasions," he writes, "but despite this intention, some water companies are responsible for up to 200 discharges of raw untreated sewage into our coastal waters each year." 

How often do you worry about the quality of your drinking water? Never 👎 Sometimes 😟 Often 🙁 Always 😨 Click your choice to see results and speak your mind.

Further, "during heavy rainfall events, water companies will continue to discharge untreated sewage into the sea," potentially almost as a matter of course when systems are overwhelmed. 

In a world where heat-trapping pollution sends global temperatures higher and higher, exacerbating extreme weather events like rainstorms and floods, contamination risks for coastal waters seem likely to increase. Many coastal communities are already geographically and infrastructurally vulnerable to storm surges and floods as sea levels rise, so they may face compounding problems.

Researchers are developing new water treatment technologies, such as ultraviolet disinfection and phage applications, but many of these are currently too expensive to implement at scale. Sewage contamination isn't exactly the flashiest cause to root for — making some noise about it could improve investment in R&D so that one day these innovations might work where they're needed most.

In the meantime, if you're swimming, surfing, paddling, or otherwise recreating in public waters, it's best to be cautious. According to the Centers for Disease Control and Prevention, you'll want to do your research, observe the actual water quality on site, never drink unclean water, avoid swimming if you're sick or have an open wound, and make sure to shower before and after your swim.

"Whilst we're waiting for the improved management, innovation and investment that is required to solve the issue and save our seaside, don't bury your head in the sand regarding water quality," warns Cox. "Check before you swim. Afterall, prevention is always better than cure."

Join our free newsletter for good news and useful tips, and don't miss this cool list of easy ways to help yourself while helping the planet.