Don’t Flush Me

Leif Percifeld descends into the New York underworld with his sensor for detecting sewage overflows. Photo: Steve Duncan/Undercity.org

“That’s all raw sewage,” yelled Leif Percifield over the roar of rushing water. We stood 15 feet underground on a ledge, watching a tide of human waste below us as it was sucked into a pipe headed for a treatment plant along Brooklyn’s East River.

Here Percifield, a graduate student at Parsons, who describes himself as a “Hacker, Interactive Developer, and Geek” on his Twitter page, hopes to install a prototype of a sensor that will allow New York City sewers to “talk back” to residents. Having opened a manhole cover and shimmied down to the ledge, he was paying particular attention to a door that has been designed to lift every time it rains and allow untreated sewage to flow directly into New York Harbor, the city’s number one source of water pollution.

Sewage egress point in Wallabout Channel near Brooklyn Navy Yard.

DontFlushMe is Percifield’s attempt to deal with combined sewage overflows, or CSOs, through a low-cost solution that engages locals. He plans to install sensors that detect rising water levels in all of New York City’s combined sewers (those that receive both waste water and rainwater) and alert neighborhood residents when levels reach the point of risk. The sensor would send information to a database to be distributed by text message to neighborhood denizens. New Yorkers could opt not to flush their toilets until levels recede and thus prevent fouling.

A New York City map designed by the GIS expert Liz Barry of Public Laboratory (a draft version for one that will allow users to locate the CSO nearest them) reveals how common CSOs are: there are 460 in New York City, funneling 27 billion gallons of raw sewage into local waters each year. (A recent video on the DontFlushMe website shows the repugnant effects of Tropical Storm Irene.)

DontFlushMe’s technology consists of an ultrasonic range sensor that Percifield designed and assembled. It protrudes from a waterproof Pelican case, which houses the wiring and mobile phone.

Percifeld’s device for detecting and notifying residents about overflows packages a homemade sensor with a mobile phone.

Percifield’s prototype is already in need of iteration. It turns out that the mobile phone the sensor relies on to output data cannot find the network underground.

And there are other design challenges. “Each CSO is different in its construction — where it is in the road, how the pipes are arranged, how accessible they are,” said Percifield. Each sensor will need to be tailored to the particular CSO location it is housed in.

Currently Percifield is fundraising on Ioby for $2,265 to purchase the sensors and cases, which cost about $140 each.

The model’s simplicity is part of its promise. “The system could scale to an infinite number of users and a variety of places,” Percifield said. “The website can be easily deployed to different cities around the country.”

It seems that one part of the battle will be getting the sewers to talk to New York City residents. The other half of that fight might be getting people to listen.