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While teaching in Uganda in 2010, American college student Kathy Ku noticed that both she and her host family were getting sick a lot from drinking the water. She kept thinking about the problem even after she was back in school at Harvard University, designing a ceramic water filter and getting other students involved. In the middle of her junior year, she took a year off to pursue the idea in earnest.

Ku wasn’t aiming just to bring water filters into Uganda. She wanted to actually make them there, sourcing the needed clay and sawdust locally. Now, five years after that exploratory visit during her year off, Ku and co-founder John Kye have a full-fledged water filter factory near Kampala. Their organization, Spouts, has grown to more than 40 staffers and distributed about 14,000 ceramic filters, which remove 99.9 percent of bacteria.

Here, she fills in details about the journey you see in the video above, and tells us what she plans to do next.

Can you remember a moment when a switch flipped and you decided to go after this problem of dirty drinking water in Uganda?

Yeah. There’s this method of cleaning your drinking water by leaving it out in clear plastic bottles in the sun. So I figured, OK, let me try that. I took a swig of the water and essentially spit it back out because it tasted like burnt plastic, and it was really warm as well. It’s a very effective way of treating your water, but I thought there had to be a better solution that people would actually like to use.

And then how did you come up with the filters that you’re making now?

I spent the next year and a half just doing basic research, trying to figure out what was out there. I had worked with different water filters in the past with Engineers Without Borders, so I had some background and knew what I thought would be a good fit for Uganda. So then I went back to school, I worked on the design but also had a small team of other interested students reaching out to local organizations to gauge their interest and their experiences with the water sector in Uganda.

You got a lot rejection shopping the idea around. Why? What was the reasoning?

In general, we were talking to development agencies, and I don’t know very many development agencies who do production of material themselves. So when organizations were saying, no, we don’t go into manufacturing, but we would be happy to partner with you if you do start making filters, that’s when we decided we would do the production ourselves. Because people were interested in the product, they just didn’t want to do manufacturing. And to be fair, manufacturing in Uganda is not the easiest thing in the world.

You describe a pretty tough time at your first proper factory in 2014, where you were also living at the time.

The factory used to be an old chicken farm that we had remodeled to fit our needs. It was affordable, at a decent location and it had buildings in place. The downside was that chickens had already lived there, so it was infested with fleas. So we had a huge problem with fleas when we were cleaning out the place and trying to move into there.

But you get used to things pretty quickly. We didn't have any running water, and our rooms were separated by curtains with no ceiling, so if you’re sneezing or snoring in one room, you can hear everything else that’s going on on the other side. We stayed there for about a year. It was fun then. To be fair, I wouldn’t do it again now. We were just trying to get things done as quickly as possible.

What made you decide you had to take a year off and really do this?

To be honest I hadn’t really thought about taking that time off until [one night] during dinner, one of the resident advisors was like, well, Kathy, it seems like you’ve put a lot of time and thought into this. Why don’t you just go ahead and do it? And I was kind of like, yeah, I guess, why not. So I think the decision was probably within an hour of that dinner.

I knew that unless I took that dive, nothing was ever really going to come out of it. There’s only so much that you can do if you’re not out on the ground. I had zero skill sets when it came to understanding how to run a business, so the first five months [of the year off] I interned for a consulting firm [in Korea] while trying to better understand, like, how do you look at a balance sheet? I could barely balance a checkbook.

In the beginning, it would take you a whole day to make a few filters. Now you’re making how many?

Now our factory has the capacity to make 10,000 filters a month. We just moved into a new place and we’re closer to 1,500 to 2,000 filters a month now, but it’s much bigger, and it has the machinery and the capacity to do a lot more. This factory [in Nakawuka, about 9 miles from Kampala] we built from bottom up. We designed the layout ourselves and built it so that we would grow into it. We are looking forward to settling in here for a long period of time.

I will be heading to Stanford medical school in the fall [and am working on the transition plan for Spouts]. It’s a great feeling to have to realize that you don’t have just a company. You have an organization, you have a structure that can run without you. So I’m really excited about that.

What is it like to see the impact of what you’ve accomplished?

That’s the funny part—you don’t realize how much things have changed until you take the time to look back. And it’s not just oh, a year ago we were somewhere. It’s like, three months ago we were doing something really stupid. I’m not a very reflective, emotional person. I’m kind of like an OK, we need to get s**t done kind of person. I still feel like I haven’t done very much. This is just the beginning.

This interview has been edited for length and clarity.