E. COLI
Combined Sewer Overflow, or CSO, happens when stormwater and household sewage share the same pipe system.
01 / Combined Sewer Overflow
What comes out is not just water.
CSOs flood waterways with microbial pathogens, suspended solids, chemicals, trash, and nutrients that deplete dissolved oxygen.
02 / What comes out
The infrastructure causing this is 150 years old.
The awareness of it is almost nonexistent.
And it happens every time it rains.
03 / Public condition
Water / Waste / Risk
HOW
CSOS
HAPPEN
When flows exceed twice the design capacity,
a mixture of stormwater and untreated sewage discharges directly into the city's waterways to prevent it from backing up into homes and streets.
Not an accident. A pattern.
About 60% of New York City runs on a combined sewer system.
398 outfalls discharge into the city’s waterways.
Approximately 18 billion gallons of combined sewage are discharged annually.
It only takes a tenth of an inch of rain per hour to trigger one.
Outfalls
across
the city
The map makes the system visible as a distributed waterfront condition, not a single isolated site.
Most people who walk along the waterfront after a rainstorm have no idea the water they are standing next to just received a direct injection of raw sewage.
The infrastructure causing this is 150 years old. The awareness of it is almost nonexistent. And it happens every time it rains.
E. coli
as signal
Combined sewer overflow discharges and stormwater runoff are the primary contributors to fecal pollution in the NYC waterways.
The main thing they carry is bacteria. Pathogens identified in CSO-impacted waters include E. coli, Salmonella, Campylobacter, norovirus, and Giardia, and recreational exposure to these waters has been directly associated with increased risk of gastrointestinal illness, with children being among the most vulnerable groups.
E. coli are bacteria that live in the intestines of humans and animals. While most strains are harmless, some produce toxins causing serious illness.
The highest concentrations of fecal bacteria in urban waterways typically occur after precipitation, driven by CSO events.
24+
hours later
Current lab-based E. coli testing can take more than 24 hours.
This creates a delay between possible contamination and public knowledge. During that window, people may already have walked near the water, touched it, kayaked in it, or allowed pets to interact with it.
Our project responds to this delay by asking how water risk can become more visible before it becomes personally felt.