By Yiting Sun

Frances Knickmeyer cut open the wrapping of the water barrel. Photo: Yiting Sun

In the 14 degree cold, Frances Knickmeyer sawed away at a plastic pipe in the courtyard of 795 Garden Street, an apartment building close to the Bronx Zoo. She then handed the shortened pipe to Mike Mendez, who was sitting on the top of a 500-gallon water barrel, trying to connect the barrel to another pipe sticking out from the building’s red-brick wall.

“Hope this one will fit,” said Knickmeyer, a conservation crew member of the Bronx River Alliance, which is a non-profit organization working closely with the New York City parks department to restore the river.

The duo and two other colleagues were installing a rainwater harvesting system for the building, which then could direct rainwater from the roof into the barrel where it would be stored until it could be used later for gardening. Starting this spring, 795 Garden Street will have a new community garden in the building’s courtyard.

But the value of a rainwater harvesting system extends far beyond one building’s attempt at water conservation and recycling for gardening. In fact, the Bronx River Alliance’s program also plays an important role in keeping the Bronx River, the only freshwater river in New York City, clean.

“In the Bronx and most of the city, the storm water runoff goes into a combined sewer system,” said Robin Kriesberg, ecology director for the Bronx River Alliance. “When there is a heavy storm, it’s too much for the system and it can’t process all this water.”

The excess unprocessed water ends up in the river, according to Kriesberg. During normal dry weather, all the sewage and rainwater automatically flows into underground pipes and is directed to sewage treatment plants. But when the amount of water exceeds the sewage system’s capacity, and the pipe swells up, as it often happens during storms, the excessive amount of water flows into the river.

Kriesberg said this has caused a lot of water quality problems in the Bronx River and other bodies of water around the city, because the rainwater runoff picks up contaminants and bacteria as it flows. A state environmental official, who spoke on background, said this problem is especially demonstrated in urban areas with lots of impervious surfaces like paved roads. Rainwater harvesting systems, like that of the Bronx River Alliance, alleviates these problems by reducing the amount of storm water runoff discharged into the river.

“When the snow melts, the water would carry salt and all kinds of potential pollutants with it into the combined sewage system,” said the state environmental official. “The harvesting system is a volume-reduction practice.”

According to the state environmental official, the benefit of the harvesting systems is accumulative. The positive impact on the Bronx River’s water quality could only take place if they are installed widely.

In 2009, the conservation crew received a grant of about $100,000 from the Bronx River Watershed Initiative, a program within the National Fish and Wildlife Foundation that funds green projects through environmental violation settlement money. The grant has allowed the crew to install harvesting systems for free. So far, this grant has supported installations of rainwater harvesting systems at seven buildings along the Bronx River.

Mike Mendez was connecting the pipes. Photo: Yiting Sun

However, by this spring, this grant will run out. Knickmeyer said the grant would fund two more systems and then the rainwater-harvesting program would have to come to a halt.

The conservation crew is not certain of additional funding sources yet, but they are thinking about some possible less costly methods to spread the word about the benefits of rainwater harvesting.

“The ideal way would be for people to be educated through workshops to find out how to install their own rain barrels, so that they could do it themselves,” said Kriesberg.

She also hopes the city would make these rainwater harvesting systems more affordable, and enticing, for residents with giveaway programs and financial incentives.