In early August, Newton, Massachusetts-based water technology company Desalitech withdrew 4,000 gallons from Boston's Charles River. After purification, the water was delivered to six local breweries for a beer-making competition.
"The Charles River is one of the biggest icons of Boston. Being able to drink it is really tapping in one of the biggest symbols of the town," said Nadav Efraty, Desalitech's CEO. "Our company has reinvented the purification and reuse process in a way that enables us to almost completely eliminate the waste of water."
The company upgraded a traditional process called reverse osmosis to treat the water and clean it for reuse. Reverse osmosis uses special membranes to block salts and contaminants, producing purified water and a stream of concentrated pollutants.
Reverse osmosis systems typically operate around 75% water efficiency, wasting about 25 gallons for every 75 gallons of purified water, according to Efraty. For the Brew the Charles project, he said, there was 98% efficiency.
According to Bob Zimmerman, executive director of the Charles River Watershed Association, swimming or boating in the river was once unheard of, let alone drinking from its waters.
"Fifty years ago, when my organization was formed, the Charles literally ran in colors" stemming from local industry waste, he said. "If someone were to offer me a beer that had been made in the 1970s from Charles River water, my reaction would have been 'No way; that's death in a bottle.' "
As recently as 1996, raw sewage pollution in the river was severe enough that it failed state swimming standards up to 80% of the time over the course of the year, Zimmerman recalled.
Then, authorities launched efforts including preserving wetlands to filter out pollutants; promoting construction of modern wastewater plants, reducing sewage discharges; and enforcing the 1972 Clean Water Act.
Thanks to the ongoing efforts of the Watershed Association and local authorities, the US Environmental Protection Agency gave the river a B+ in 2015, up dramatically from its D in 1995.
According to Renata von Tscharner, founder and president of the Charles River Conservancy, about $500 million has been invested over the years to clean up the water and bring the region's main waterway back to life.
"It's still got its issues, but you can boat on it safely, occasionally swim in it safely, and we're working hard to get it the rest of the way," Zimmerman said.
The shift in the way locals perceived the river was captured by the 1966 song "Dirty Water" by the Standells. Once a gloomy depiction of the city and its river, it is now the closing song for victories when baseball's Red Sox win at Fenway Park. Zimmerman sees it as "an anthem of rejuvenation and restoration for the city."
In September, about 1,000 people attended the closing party for Boston's HUBweek innovation festival, tasting beers made from the Charles' water.
Adam Romanow, founder and president of Castle Island brewing company -- which won the People's Choice Award -- grew up in the Boston area and typically uses the Quabbin Reservoir in Central Massachusetts as his brewery's main water source.
"We don't normally use the Charles River, but we got lucky this time," Romanow said. "The water that we got was actually slightly better than the quality of water that we usually get straight out of the tap."
Tasters appeared mostly intrigued and undaunted by the beers' origins. "Why would I be concerned? It tastes great," Rachel Motz said.
The event was also part of an initiative to create a permanent swimming area in the Charles.
"There used to be swimming in the Charles River until the 1950s. So, many people have fond memories of swimming in the river," von Tscharner said.
Until then, fans will have to settle for drinking it.