Soon enough, robots may wander permanently in our sewers, just below our homes and neighbourhoods, analyzing our diets and our health as they suck up what we flush down.

It's already started under the streets of Cambridge, Mass., venerable home of the Massachusetts Institute of Technology.

Canadian architect Newsha Ghaeli oversees a team of lab-coated MIT research fellows staring down an open manhole cover into the oozing sludge below. Down there are the answers, and the hope of detecting viral outbreaks long before doctors are even called, using a system of sensors that quickly and inexpensively monitors public health.

Robots like this one are being lowered into city sewers to sample human waste. In doing so, they may be able track people's health and look for diseases in different neighbourhoods. (CBC)

The team works on a project called Underworlds. They lower Luigi — a tube-like robot — to just above the sewage. Then, controlled by a smartphone app, Luigi drops tubes into the stream. A small pump sucks up the liquid and runs it through a filter.

Subsequent analysis in the laboratory typically finds 50,000 different bacteria, a host of viruses and other matter that, until a short time earlier, were inside a person.

"We are learning about the people that live in each of those neighbourhoods," researcher Jessica Snyder explains. The data can provide information about the residents' health habits, nutrition, and their lives.

By the time sewage sludge reaches a treatment plant, it's been watered down and is useless as a sample. But where it exits homes, as much as 70 per cent can be human waste and a rich source of biological information.

Salt intake test

MIT has partnered with Kuwait City in this project. Its residents have some of the highest salt intakes in the world, which can lead to a variety of health problems. The Kuwaiti government is working to change that — but needed a way to measure salt intake honestly and widely. So Luigi analyses poop and — over time — can tell if neighbourhood salt levels are declining.

The researchers now run specific projects manually, measuring repeatedly in the same spot over several weeks or months. They need to take the robots back to the lab to analyze the samples.

Canadian architect Newsha Ghaeli holds the sewer robot Luigi. Once it has been lowered into the sewers, it's controlled by a smartphone app. A small pump sucks up sewage samples and runs them through a filter. (CBC)

In the future, however, they plan to have self-propelled robots with extremely long battery lives, capable of navigating among neighbourhoods, analyzing sewage contents while in the sewer itself and relaying information wirelessly to a central authority.

"One of the holy grails of this project during its inception was to identify viral outbreaks," says Snyder.

Long before people visit a doctor's office, they visit the toilet. So a highly contagious pathogen, such as norovirus or Ebola, could be identified soon after infection — and treatment could be targeted at that neighbourhood.

And once patterns of sickness are visible for certain illnesses, such as the seasonal flu, says Snyder, "medical support would be able to anticipate these outbreaks and help mitigate them."

But the work on virus identification is in its earliest stage. It will be years before science is able to quickly identify specific viral dangers hidden in the mass of excrement, urine and wastewater. Work is being done in New York City and Shanghai to isolate and categorize the thousands of micro-organisms.

Tracking illegal drug use

More immediately though, the city of Boston is now using Luigi (and its predecessor Mario, both named after the protagonists of the sewer-based video game Super Mario Bros.) to identify neighbourhoods where heroin use is spiking. Boston Mayor Marty Walsh then plans to focus law enforcement and health resources on those areas.

Right now, samples need to be brought back to the lab for analysis. But in the future, researchers hope the robots will be able to do the analysis right in the sewers and report back to them wirelessly. (CBC)

In Europe, a continent-wide study of sewage revealed cocaine and ecstasy use was greatest in large cities on weekends, but cannabis and methamphetamine use was more evenly distributed throughout the week.

In Chicago, work is being done on a battery-powered sensor housed inside a suitcase-sized casing that runs DNA amplification reactions. It can search for 385 commonly found organisms — such as different kinds of bacteria, in a single sample of wastewater — and transmit the findings via Bluetooth.

Few cities are using the Smart Sewer technology worldwide, but as the capabilities of robots expand to work longer underground with the ability to rapidly analyse micro-organisms, more are expected to adopt the idea.