The famous Little Mermaid statue in Copenhagen's harbor. News Oresund / Flickr

Residents of the Danish capital swim in its harbor and drink some of the world’s purest tap water—taking care not to waste it—thanks to decades of government efforts.

If you lived in a metropolis roughly the population of Baltimore, would you consider swimming in its waterways?* In the United States, the response is likely “not a chance.”

But in Copenhagen—Denmark’s capital of 1.2 million people, crisscrossed by canals and practically surrounded by water—jumping into the harbor that splits the city in half isn’t reserved for the brave few who can stomach sludge. It’s a government-sanctioned, and completely safe, part of everyday life. In 2002 the city opened Islands Brygge, the first of its four “harbor baths,” right in a bustling downtown neighborhood. Now a dip in the harbor (even if it’s an impromptu after-dinner swim in your underwear) is a regular occurrence for many Copenhageners.

The harbor wasn’t always so welcoming. As recently as 1995, wastewater was piped where swimmers now splash. Contamination from oil spills, industrial waste, and algae also made the water unsafe. In the 1960s and early Seventies, dead fish were not an uncommon sight.

However, a sophisticated alarm system developed by a private Danish company predicts when and where an overflow will occur based on rain forecasts, existing water levels, and tides. It alerts city employees via mobile phone so they can shut down swimming areas immediately if needed—a rarity, but essential for public safety and peace of mind.

According to Jørgen Lund Madsen, Copenhagen’s head of Water and Environmental Impact Assessments, it took 3 billion Danish kroner (about $440 million) to reroute wastewater, build overflow barriers, and create underground water-storage vessels to ready the harbor for swimming. Even now, during heavy storms, rainwater can still back up into sewers and pollute the harbor.

Kim Dorff, a native Dane who has lived in Copenhagen for 18 years, frequents harbor baths during the summer. He appreciates the convenience of swimming lanes and onsite showers (saunas even await cold-weather swimmers on the shore at Islands Brygge). He says he has never been fearful of the water quality, nor has he known anyone to have reservations about diving in.

The harbor baths are just one manifestation of a culture of prioritizing water that gained traction in the early Seventies, after Denmark’s Environment Ministry was founded. This mindset has taken the city from pumping sewage into its harbor (when it was known to come up to street level) to unwavering trust in the quality of public water and an aversion to wasting it.

It could not be more different from Flint, Michigan, which recently declared a state of emergency due to unsafe levels of lead and trihalomethanes. Across the U.S., variables such as sourcing, pollution, differing treatment methods, and aging infrastructure can cause huge gaps in water quality. These are non-issues for Copenhagen residents, regardless of their socioeconomic status or neighborhood.

Copenhagen is virtually immune to events like those in Flint, despite the city’s age (its first incarnation was founded in the 10th century), history of pollution, and proximity to industrial and agricultural sites, as well as shipping activity. The primary reason is that tap water is sourced solely from Denmark’s heavily protected groundwater reserves—including some beneath the capital itself—rather than surface water. Public drinking water is now so clean that it’s better than bottled water, says Mayor of Technical and Environmental Affairs Morten Kabell—and that’s without chlorine or other chemical processing (only aeration, pH adjustment, and filtration).

Dorff, who has lived abroad and travels frequently for work, says drinking tap water without a second thought is in fact one of the things he misses most when traveling, and it’s something most Danes never even think about until they go abroad. “It feels strange for me to come to the U.S.—and other countries—and see the consumption of natural resources [there],” he says.

Kabell says the only instance of less-than-perfect water quality he can recall is when a bird once found its way into a reservoir and drowned. City residents were warned to boil their water for a couple days, and afterwards it was clean water as usual—no hard feelings.

“[The city was] open and honest about what happened,” Kabell says. “People took it as what it was—an incident. Most Copenhageners were saying, ‘We’re really impressed that you control the water so much [and] that we didn’t have one illness.’”

Kabell says buy-in from Copenhageners is a huge part of why the city is in such a good place. The benefit to residents is clear: a dependable supply of pure water. In return, they willingly do their part, which means conservation—and taxation. The average Copenhagener only uses about 26 gallons a day, compared to the 80 to 100 gallons used by the average U.S. citizen. Water taxes provide a strong incentive to cut back; according to Global Water Intelligence, a UK analysis group, Danes pay the highest water rates in Europe, at 6.33 Euros per 1,000 liters or 264 gallons (compare France at 3.35 Euros and Sweden at 2.73).

Public awareness has played a role too. “We’ve said, ‘If we are to have clean water in the future, then we need to be sustainable in our water usage. We need to use less water,’” Kabell explains. “Copenhageners have sort of accepted that task. For them, it makes good sense.”

Danes who grew up in the Seventies through Nineties, like Dorff and Kabell, remember being subject to school-focused campaigns around environmental responsibility and conservation. Dorff recalls a giant water meter once being placed in the middle of town to encourage responsible usage. Denmark mandated labels rating the energy efficiency of household appliances in 1990, and now it sets minimum standards for “ecodesign”; more efficient appliances have helped Danes reduce the water as well as energy consumed by their dishwashers and washing machines.

Water quality and conservation have become big business, with both the public and private sectors developing cutting-edge technologies like the harbor alert system, as well as the state-of-the-art Danish Groundwater Mapping Program.

Cloud bursts, like the 2011 one that dumped several inches of rain on Copenhagen in a matter of hours, have prompted new climate adaptation plans. (Martin Lehmann / AP)

Just outside the city, Herlev Hospital recently launched its own wastewater treatment site (Madsen recalls the director publicly drinking a glass of what was once hospital wastewater). In 2017, Billund BioRefinery will open about 200 miles outside Copenhagen, the first site in Denmark to conduct energy extraction from wastewater sludge.

Despite all the progress, Madsen and Kabell agree that the city’s pride in its advancements, as well as Copenhageners’ habit of taking their water for granted, may be a double-edged sword. The current generation has been indoctrinated about conservation so much that it’s a part of everyday life, but out of sight, out of mind may not always be a good thing—especially with a changing climate and an increase in cloud bursts that cause serious damage and threaten basic services.

“There’s a risk that [the groundwater] will be polluted in the future because of all the farming in Denmark,” says Madsen, adding that the next generation, or the generation after that, may have to plumb deeper aquifers or find new ways of getting fresh drinking water.

He says working ahead is the only way to ensure that Copenhagen continues to lead the worldwide water movement, regardless of how comfortable the city might be now. Kabell agrees that foresightedness is the best plan of action: “This is a challenge that applies to us, and it will apply to the rest of the world at some time.”

*Correction: This post erroneously compared the population of Copenhagen to that of Dallas and has been updated.

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