- [Narrator] Chances are you don't think much about your sink.

It's one of those out of sight, out of mind places.

Turn the water on and wash the dirt and grime and food waste all away.

It turns out you should think about your sink because there's a lot that lives in it.

- Microbes really like a couple of things, and two of the primary features that they really like is moisture and food, and that particular environment is very conducive to allowing microbes to survive and colonize and actually expand.

- [Narrator] And no matter where the sink is installed, bathroom, kitchen, laundry room, lavatory, wherever, the sink is nirvana to this microbe.

Meet Bacillus velezensis.

- And depending on how we operate those sinks, the types of things that we put down the sinks, that will lead to different types of microbes surviving and growing in those particular spaces.

- [Narrator] And if you think you do a great job cleaning the sink, well, there's a catch.

- We utilize anti-microbial soaps.

We utilize a lot of different reagents that will clean and kill particular microbes, and so what happens is microbes that are actually more dangerous, that may carry antibiotic resistant genes, for instance, or are more virulent, are able to survive and outcompete the good microbes, will be enriched in those particular spaces.

So while cleaning has some advantages, it may also have some negative consequences.

- [Narrator] Researchers at Duke University's shared materials instrumentation facility are studying the microbiome of the sink.

In other words, what lives in your sink?

It's part of a larger research project looking at how the microbes in what's called the built environment, the place where people live, work, and play, interact with people.

After all, Americans spend 90% of their time indoors.

- In those spaces, there are microbes everywhere.

They are on the surfaces, they are in the water, they are in the air and so our center is really focused on understanding how those microbes and the humans that occupy those spaces intersect.

- People, and the built environment, things are always moving.

Things are always changing, bacteria is always growing.

It's not a matter of where, it's a matter of when.

- [Narrator] And researchers have discovered that every time you use the sink, microbes take advantage of tiny water droplets to enter the environment.

- We turn our faucets on and water comes down the faucet.

There will be a certain cloud that is generated, so you can think about a biological cloud, and so those organisms that were in that one location may spread, and then through our own touching of those particular surfaces, we can spread them into other places.

- [Narrator] While most microbes either help human health or have no effect on human health at all, there are some pathogenic microbes that can make us sick.

That's why scientists in the sink study sample the entire sink to find out what's living there.

- And I'm gonna go not only the surface of my sink, but also just that initial beginning of the drain 'cause I want to know not only what's living right on that surface, but what's living right underneath.

So I'm gonna go under our little plastic liner.

- [Narrator] So far their sink studies shows that it's not only the cleaning solutions that determine what microbes live in the sink, just how the sink is used also makes a difference.

- When we talk about in the kitchen food or different foods liked by different bacteria, so I'm actually creating a food environment for a preference of different bacteria that could grow.

- Scientists have also discovered that while microbes live all over the sink and the drain, the highest concentrations of bacteria are found in the P-trap.

That's the curved pipe underneath the sink.

- It is essentially where water will remain even when you're not using the sink, and that stagnant area is where a lot of microbes like to accumulate.

Bacteria live in kind of two forms, planktonic.

Think about those as plankton in the ocean.

They're free floating and going everywhere.

And then there's the biofilms, which you feel kind of a slippery spot on the bottom of your shower, and that is a bunch of bacteria which have produced these sticky tough substances that adhere them to surfaces.

So right here in the P-trap is a perfect spot for them to form biofilms.

So here we have kind of a model test bed that we have.

We have three sinks in parallel and three P-traps that we can sample from.

And here we can monitor how biofilms grow, the stages they go through, how one microbe can slowly take over kind of a community.

- [Narrator] And scientists have also found the microbes in the P-trap don't just stay there.

They can climb up the pipe.

- While they start in the P-trap, they'll also move up the tailpipe and all the way up to the drain, and so you know from cleaning your sink or your drain or your faucet, that there are microbes that grow.

So you'll see pinkish or black or white, different colors of microbes in those different places.

Also around the sink basin and the drain cover.

- The question then is how to build a better sink.

- So we're looking at the importance of materials and material characteristics on bacterial attachment.

We're thinking about attachment because it's the first stage in biofilm formation.

- We're really wanting to figure out what are the best approaches for managing the microbiome in a way that leads to beneficial organisms accumulating and limiting the spread of those particular pathogens.

And so that is thinking about what are the products that we utilize to clean our sinks?

And what are the effects of those on those microbiomes in those sinks?

What are the materials that we utilize to construct those sinks and how those may lead to particular attachment of organisms.

But it could also be just thinking about the architecture of your sink, thinking about the types of faucets that we utilize, where our drain covers are.

So we're really interested in thinking about all of that in a holistic way.