James Harper

Smart toilet designs in Cambodia held promise, but a key piece was missing

Alexander James Servantez — Wed, 19 Nov 2025 20:58:52 +0000

Smart toilet designs in Cambodia held promise, but a key piece was missing Alexander Jame… Wed, 11/19/2025 - 13:58

Alexander Servantez

A smart toilet design introduced in rural Cambodia was supposed to change lives—keeping families safe and protecting the environment.

However, while households reported that they liked the new system, a crucial piece was missing: using it correctly.

James Harper, an assistant teaching professor in the Paul M. Rady Department of Mechanical Engineering at �鶹��Ѱ��Boulder, recently led a behavioral study analyzing toilet use in Cambodia. The work, conducted through Harper’s own research consultancy Realize Research in partnership with international development organization iDE, assessed rural households using a backyard sanitation system designed for families to treat human waste themselves.

“Here in the States, we don’t need to think about clean water coming from our tap or having a toilet that flushes, but there are plenty of places around the world that do,” said Harper. “Cambodia is a country of about 17 million people where sanitation systems are lacking. There have been a lot of innovations to help bring new infrastructure and practices to rural areas of the country, and this study examined one of those innovations from a behavioral perspective.”

A man digging a pit for one of the alternating dual-pit latrines (ADP) in rural Cambodia.

An easy, effective sanitation solution

iDE partnered with local business owners to promote, sell, and install alternating dual-pit latrines (ADP) across six Cambodian provinces. These pour-flush toilet systems are most commonly used in off-grid locations and are an adaptation of single-pit latrines like those commonly found in U.S. national parks.

Since 2009, iDE has facilitated the implementation of over 410,000 basic, pour-flush latrines, representing nearly one in five toilets in all of rural Cambodia.

The ADP is essentially a new second pit and is sold as an upgrade to an existing single-pit latrine that is currently full of waste. When one pit fills—usually after two to five years of regular use by a household of five—users can switch to using the empty second pit.

When the initial installation is performed, the service provider mixes hydrated lime, a common soil conditioner used globally in agriculture, into the first pit to speed up the process of treating the waste and kill pathogens that endanger humans.The toilet is then connected to the new second pit.

After the second pit fills, users are encouraged to call their original service provider or they can empty the first pit safely using shovels and buckets, and then reconnect their toilet back to the first pit. The lime mixture and storage time remove most pathogens after two years, making the treated waste easy and safer to compost, allowing the cycle to repeat indefinitely.

It’s not the most glamorous engineering project, but Harper says ADPs are extremely effective at killing off dangerous pathogens, especially in areas with limited infrastructure. The waste they produce can be used, somewhat surprisingly, for agricultural purposes, as well.

Human waste is replete with nutrients that plants love, so as long as pathogens are removed, human waste can be a great fertilizer.

“Lime is a cheap agricultural amendment that’s commonly used around the world to change the pH of soil to improve crop production,” Harper said. “We use it to raise the pH in a full pit to kill pathogens that endanger humans. Then, that human waste can be used as a fertilizer to make crops grow better.”

The interesting, important results

From a theoretical standpoint, ADP latrine implementation in Cambodia was sound. It was safe, cost-effective and came with a number of potential benefits for the area.

However, the team recognized early that long-term use of the system depended on the engagement and behavior of the households themselves.

A man putting the finishing touches on an ADP in rural Cambodia.

After multiple training sessions and allowing families to manage their ADPs themselves, iDE and Harper surveyed 765 households to see how well people were using the toilets and following the recommended guidelines, particularly those about waiting 2 years before emptying and switching their pit connections. Despite a general understanding of the required steps and expectations, they found that follow-through among households was inconsistent.

According to the survey, only 40% of people could recall certain details of recommended ADP maintenance, including how long before emptying a pit can be done safely. In fact, not one household in the entire study waited the recommended two-year period before emptying, potentially exposing themselves and others in their community to health risks via pathogen exposure.

Harper says there were clear motivations for the results. Some families opted to empty pits early before hosting guests during cultural events. Others simply reconnected their old pits to their toilets without emptying the dried, compacted waste. But overall, households just did not want to manage their own waste—for obvious reasons.

“Ultimately, what the study highlighted was the difference between theory and practice,” said Harper. “We learned that households can’t—and actually shouldn’t—be relied upon to completely manage their own waste, and that’s a reasonable finding. We don’t manage our own waste in the States; we just flush and forget. So, why would we expect something different from people in Cambodia?

While the ADP could be a great product, its use in the real world is different than we assumed during design, and that’s why the design must be improved going forward—to meet the need while working within the real-world constraints of our users.”

iDE will use the results of this study to pivot and experiment with other solutions. They are currently testing and scaling up a service-based approach where waste can be disposed of safely on the household premises by a trained service provider. All a household needs to do is call when they need help emptying their pits.

But Harper and his iDE colleague Tyler Kozole also hope the study can be a moment of learning that all engineers across any discipline can benefit from, too.

“We recognize that this research indicates what could be viewed as a type of failure in our work,” said Kozole, director of iDE Cambodia’s Wash, Sanitation and Hygiene (WASH) program. “We’re broadcasting this research to advocate for embracing and learning from failures. If the whole sector embraced this mindset, we’d solve problems faster, use our resources more efficiently and ultimately make the kind of impact we’re trying to see in the world.”

Assistant Teaching Professor James Harper recently led a behavioral study analyzing toilet use in Cambodia. Their goal was to introduce a new, smart toilet design that can keep rural households safe and protect the environment. But while households reported that they liked the new system, a crucial piece was missing: using it correctly.

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Climate change is encouraging unsanitary toilet practices among vulnerable communities

Alexander James Servantez — Fri, 06 Dec 2024 19:34:09 +0000

Climate change is encouraging unsanitary toilet practices among vulnerable communities Alexander Jame… Fri, 12/06/2024 - 12:34

In a study conducted by Assistant Teaching Professor James Harper and his consultation company Realize Research, LLC, it was found that regions where heavy storms and floods are more prevalent cause households in those areas to stop using and maintaining their toilets. Toilet dysfunction is a huge source of pollution, can increase the burden on water treatment systems and is a major risk of human health.

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New PhD research area allows students, faculty to explore engineering design in a wider context

Alexander James Servantez — Wed, 27 Nov 2024 19:04:13 +0000

New PhD research area allows students, faculty to explore engineering design in a wider context Alexander Jame… Wed, 11/27/2024 - 12:04

Alexander Servantez

At the Paul M. Rady Department of Mechanical Engineering, the process and application of design is everywhere.

Students are constantly designing tools and technologies. Faculty members are launching successful startups on the backs of their own designs. In just the past two years, Venture Partners at �鶹��Ѱ��Boulder has supported 10 new startups featuring inventions designed by ME faculty and students.

But earlier this fall, the department took nearly a decade of development to a whole new level by introducing a new research area in design. This focus area, geared toward PhD students, involves the study of the design process and how various contexts (environmental, psychological, political, etc.) affect the artifacts that today’s engineers aim to create.

It’s the next step in the department’s design growth, building on the current MS design framework and the large network of undergraduate design courses made possible by Design Center Colorado. ME faculty and staff have worked tirelessly over the years to build this infrastructure and weave elements of design throughout all the other focus areas in the department. The new design PhD focus area represents the next iteration.

Grace Burleson, assistant professor of mechanical engineering, was a key player, among others, in the creation of this new concentration. She believes the focus area will help �鶹��Ѱ��Boulder researchers enhance the practice of design, and advance design methodologies throughout many engineering disciplines to tackle the difficult societal challenges we see today.

“Design has been happening in the department since the beginning. It’s embedded in mechanical engineering and our other focus areas,” Burleson said. “However, that framing makes it challenging to focus on design as a scientific study.

“Our engineers are being asked to solve much more complex issues than ever before, and we need to expand our thought of design in order to be successful.”

From interdisciplinary beginnings

Grace Burleson, assistant professor in mechanical engineering. Burleson is one of over 20 faculty members affiliated with the new design focus area.

The inspiration behind Burleson's research can be traced all the way back to summer 2015, nearly 8,517 miles away from Boulder.

Burleson, at the time an undergraduate student at Oregon State University, was on a research trip in Uganda studying global health and sustainable development. While conducting her research, she quickly realized that her typical engineer’s rationale was not enough to foster successful design processes. An understanding of social contexts and a whole new perspective was needed in order to do her work the right way.

From there, a whole new spark of curiosity was formed. A spark that led Burleson down a dual path threading the needle between mechanical engineering and anthropology. She studied the two areas and applied principles from each to her own work until she found a true relationship: the impact of design.

“Applied sciences have always been a pillar of design in engineering, and they always will be,” Burleson said. “But I learned that we have to broaden the scope of sciences that we are using to design our artifacts. There are cultural considerations we need to understand in order to find the effective and equitable solutions to our design problems.”

After receiving her PhD from the University of Michigan, Burleson’s next project was finding a home that allowed her to foster the next great design minds. She joined �鶹��Ѱ��Boulder’s Department of Mechanical Engineering, whose interdisciplinary approach and faculty support made it easy for her to make her mark.

“Design has been a strong focus in our department long before I joined, and I received strong encouragement from other faculty members to start the process for formalizing the focus area,” Burleson said. “I met with faculty who led design research, and we all agreed that we needed to do this.”

To the first iteration

Nicole Xu, assistant professor in mechanical engineering, showcasing her lab's bio-inspired design for robotic jellyfish.

The Design Focus Area launched in fall 2024 with over 20 faculty members from very diverse backgrounds. Some faculty members tackle design questions in the areas of air quality and sustainability. Others practice design through the lens of materials and mechanics.

This interdisciplinary structure is a staple in the field of design, which Burleson calls a “horizontal discipline.” While other focus areas might require in-depth, vertical research into one topic, design requires a wide range of knowledge in a handful of topics. It’s a holistic approach that invites students with diverse backgrounds who are looking to study design.

“When I’m recruiting PhD students, I’m looking for those diverse backgrounds,” Burleson said. “We have students from mechanical engineering, physics, even theater and law. It really lends a unique perspective to the focus area.”

Even the current research that faculty and students are conducting is multi-dimensional and exciting. Nicole Xu, another assistant professor in mechanical engineering, focuses on biology-inspired design elements for robotic mechanisms. Her lab creates aquatic vehicles that mimic the movements of live organisms for environmental monitoring.

“Engineering is often seen as a purely logical field, but we need to think more broadly about other aspects of design,” Xu said. “In my work, we apply design principles from animals to improve or expand our available underwater technologies. For other faculty, the perspective could be the emotional contexts of design science, like teamwork and collaboration.

“Design is already inherent in every engineering project, with all the different types of research in our department. But it’s never been brought to the forefront like it is now with this new focus area.”

On to the next evolution

James Harper, assistant teaching professor in mechanical engineering.

Burleson says the focus area will continue to expand as engineers apply and advance new sciences. She also mentions rumors of an increased emphasis on design practice and research across campus to leverage the university’s vast consortium of design expertise.

Assistant Teaching Professor James Harper echoes those same sentiments, saying there is ample opportunity to enhance the curriculum going forward. He even says that prospective PhD students have the opportunity as they are here to leave their mark on the department, and change the way design is taught college-wide based on their research.

“Engineers are not taught to talk to people,” Harper said. “We’re taught the technical side of things. But design relies on engineers understanding people and how products are actually used. Good design requires gathering contextual data, as well as entrepreneurial skills, and we’ve begun to teach these topics even in undergraduate engineering courses, too.”

One of Burleson’s design-track PhD students, Mark Henderson, recognizes the impact he could have on future generations. As a patent attorney, Henderson has seen lots of creators receive patent rejections on their inventions because their designs were “too similar” to others.

His research in the focus area revolves around one question: what design choices would engineers make if they already knew the “state of the art”?

“Here at �鶹��Ѱ��Boulder, I have the opportunity to use these classes and this community for design research,” Henderson said. “But there is also potential in the broader Boulder area to do industry research with the large companies that are here.

“I really couldn’t believe the fit when I chose to study design at �鶹��Ѱ��Boulder.”

The Paul M. Ray Department of Mechanical Engineering has launched a new research area in design. The new focus area, geared toward PhD students, involves the study of the design process and how various contexts (environmental, psychological, political, etc.) affect the artifacts that today’s engineers aim to create.

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