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Making New York City’s East River safe for swimming by turning a pool into an oyster

Author Jacqueline Detwiler Illustration jameson Simpson


Once upon a time, swimming in a municipal waterway wasn’t the shudder-inducing concept it is today. “In 1937, there were 14 bathhouses [on] the island of Manhattan,” says Archie Coates, co-founder of + Pool (“Plus Pool”), a 285,500-gallon swimming facility that will float on one of New York City’s waterways in 2016. Coates and his co-founders set out to return to those days of purity by making a pool full of river water clean enough for New Yorkers to swim and play in, using technology that is conceptually similar to the gills of oysters. The chlorine-free, environmentally friendly idea has captured a lot of imaginations, from the Kickstarter supporters who donated $41,000 to make it a reality to + Pool’s latest partner, Google. Here’s how they did it.


1. First, the engineers needed to know what they were up against. They partnered with Columbia University scientists and environmental watchdog group Riverkeeper to figure out what toxins were making the river water unhealthy for humans. “We always assumed it was chemicals, but it turned out to be mostly sewage,” says Coates.

2. The co-founders of + Pool then partnered with engineering and design firms Arup and IDEO to develop a three-level filtration system made out of high-tech “geotextiles” that have previously been used in wastewater treatment. As the water moves through the system, each layer removes smaller microbes than the previous one.

3. To secure permits from the city, the engineers tested the geotextiles by slowly pumping water through small tanks in the East River. Now, they’ve built a 35-foot-by-10-foot floating lab on the Hudson that filters water at actual speeds. Google, meanwhile, has helped create a user-friendly site where people can see real-time data on the health of the river.

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