There are only so many things you can do with 5,000 outdated toilets. That is, other than establish the world’s largest public commode-planter garden.

New York City, as it turns out, has been hoarding them. Over the past several years, the New York City Department of Public Education has slowly but surely gone about retiring old — some likely really old — toilets at schools across the five boroughs. (Oh, the stories those toilets could tell!) New, more water-efficient models have taken their place.

Now, in lieu of being unceremoniously being hauled off to out-of-state landfills after decades of public service, 5,000 of these porcelain fixtures are being incorporated into an ambitious marine life restoration project that aims to bolster the Big Apple’s oyster population — a population that in the 17th century was spread out across a staggering 220,000 acres of reefs but had all but vanished by the early 1900s.

You see, the benefit of reintroducing oysters to New York City, once a top shellfish destination, doesn’t necessarily involve tiny forks, a dash of lemon or a deep fryer. Along with dredging, raw sewage disposal and unchecked industrial pollution, decades of over-harvesting for culinary purposes is what helped lead to the bivalve’s decline and "functional extinction" with New York Harbor in the first place.

Now, instead of being gobbled up en masse, the oysters — reintroduced as part of the New York Harbor School’s Billion Oyster Project — will help to naturally clean New York Harbor. What’s more, oyster reefs serve as a first line of defense against catastrophic storm surges much like the surges unleashed on the city during Superstorm Sandy.

This is where the old toilets come in.

Jamaica Bay, a 31-square-mile body of water once teeming with oysters, will be the site of a large-scale oyster habitat composed of a "central donor bed" along with a quartet of smaller reefs or “receiving beds” made from clam and oyster shells and a few thousand crushed porcelain toilets. In all, 50,000 breeding oysters will be planted in the new in the new installation — the largest single installation of its kind in New York City history.

Billion Oyster Project, NYC To date, the Billion Oyster Project has restored 20 million oysters with the help of 300,000 pounds of reclaimed and recycled shells and, now, public school toilets. (Photo: NYC Water/flickr)

As a press release issued by the Office of the Mayor explains, once the installation is complete, the “hope is that the oysters will become self-sustaining, spawning seasonally and providing new recruits.”

“This oyster bed will serve multiple purposes — protecting our wetlands from erosion, naturally filtering our water and providing a home for our sea dwellers are just a few. More broadly, this oyster bed is a small but necessary step in our broader OneNYC commitment to create a more sustainable and more resilient city,” says Mayor Bill de Blasio.

Again, the reintroduced oysters will not be farmed for food as they were in the past. So don't hold your breath for any toilet-to-table NYC oysters, folks.

The installation is funded by a $1 million grant from the Department of the Interior along with a $375,000 contribution from the city’s Department of Environmental Protection (DEP). Students and faculty from the Harbor School, located on Governors Island, will monitor the new beds as well as provide assistance in their installation.

Referring to restored oyster reefs as the “foundation of an ecologically robust estuary,” Katie Mosher-Smith, restoration manager of the Billion Oyster Project,” goes on to note that the “participation of skilled young vessel operators and aquaculture technicians from New York Harbor School expands the reach of this environmental effort, building a stronger community that understands the need and has the know-how to sustain restoration of their own heavily urbanized coastline.”

Billion Oyster Project, NYC New York Harbor was once internationally renowned for being, ahem, flush with oysters. Decades of over-harvesting and pollution changed all that. Now, the city is aggressively attempting to rebuilt its oyster population but sans farming. (Photo: NYC Water/flickr)

The project comes on the heels of two, four-year pilot studies conducted in different parts of Jamaica Bay to see if oysters could survive and most importantly, reproduce, in the same waters where they once went extinct due to human activity. As the press statement explains, the pilot studies “also measured how effective the bivalves are at filtering various pollutants that affect the Bay, such as nitrogen, other nutrients, and particulate organic matter.”

The pilot studies panned out — reintroduced oysters both survived and reproduced. Ideally, the new, larger installation will demonstrate whether or not the recruitment of new oysters can also occur in a previously mollusk-barren body of water. The Harbor School will also monitor for improved water quality and keep tabs on erosion within an estuary that the Billion Oyster project describes as once being “one the most biologically productive, diverse, and dynamic environments on the planet.”

The 5,000 toilet/50,000 oyster scheme gives the Billion Oyster Project a nice bump in its ultimate goal: a New York Harbor that’s home to 1 billion water-filtering, storm-buffering mollusks by the year 2030. Only then, will the harbor be able to reclaim its previous title of “oyster capital of the world."

Matt Hickman ( @mattyhick ) writes about design, architecture and the intersection between the natural world and the built environment.