Every year, the CAS Project Challenge reminds us why student-led service matters. Students from around the world are asked to notice, to listen, and to respond thoughtfully to what is right in front of them.
This year’s winning project, Nusantara Bersih, does exactly that.
Led by three Grade 12 students, Serafina, Kayleen, and Ashley from Tzu Chi International School in North Jakarta, Indonesia, Nusantara Bersih is a project rooted in observation, chemistry, sustainability, and deep care for community wellbeing. Their work addresses a challenge that is often invisible to those who do not experience it daily: access to basic hygiene and sanitation in under-resourced communities.
What makes Nusantara Bersih stand out is not only its reach, 300 kits distributed, impacting more than 2,000 people, but the way it rethinks how cleaning products are made, transported, and shared. It is practical, low-waste, community-informed, and designed with long-term responsibility in mind.
From a moment of awareness to a shared commitment
Like many meaningful CAS projects, Nusantara Bersih began with a moment that stayed with the team.
During visits to nursing homes and other under-resourced spaces, the students were confronted with something quietly devastating: the lack of access to basic hygiene. Cleaning products, something many of us take for granted, were not consistently available, despite being essential to daily dignity, health, and safety.
“It was heartbreaking,” the team shared. “Hygiene is a daily necessity that everyone should be able to access.”
That moment became a turning point, as they began to understand it as something deeply human and deeply local. This reflection eventually formed the basis of their Grade 10 final service project, one they decided to take on together, having known one another since their early secondary years.
What does Nusantara Bersih mean?
The name Nusantara Bersih translates to “Clean Archipelago.”
- Nusantara refers to the Indonesian archipelago
- Bersih means clean, tidy, or pure
For the team, it captured both the geographical scale of Indonesia and the simple but powerful goal at the heart of the project: supporting cleaner, healthier living conditions in communities that are often overlooked.
Rethinking sanitation through design and chemistry
One of the team’s earliest realisations was that the problem was not only about which cleaning products were available, but also about how they were made and delivered.
Shipping liquid cleaning products across Indonesia, particularly to remote areas, is expensive, heavy, and often unrealistic due to poor road infrastructure. Large plastic containers add cost, waste, and logistical barriers.
Their solution was deceptively simple: remove the liquid altogether.
Instead, the team designed a solid cleaning tablet that could be dissolved into water when needed. Each Nusantara Bersih kit includes a reusable spray bottle, a pump bottle, and three biodegradable cleaning tablets. By transforming the cleaner into a solid form, the team eliminated single-use plastic, significantly reduced shipping weight. It made distribution to remote communities far more feasible, especially in areas where infrastructure makes transporting heavy liquids difficult. Just as importantly, the kits were designed as a reusable system rather than a disposable product.
Why Lerak? A local solution with deep roots
Central to the project is Lerak, a local fruit traditionally used in Indonesia for washing clothes. Lerak contains natural saponins, making it an effective cleaning agent that does not require synthetic chemicals.
The team discovered Lerak while researching possible sustainable solutions and were surprised to learn that many local communities were already familiar with it, just not in this format.
“It’s natural, locally available, and reproducible by the community,” they explained. “We wanted something that didn’t rely on imported ingredients and could eventually be made by people themselves.”
Using Lerak allowed Nusantara Bersih to support responsible production, reduce chemical runoff, and align the project closely with the local environmental context.
Building it by hand — and by science
As chemistry students, Serafina, Kayleen, and Ashley led the development process themselves. They dried Lerak peels, ground them repeatedly into powder, and refined the texture until it could dissolve properly. Much of this work happened between Ashley’s home and the school labs, using blenders, re-grinding methods, and a lot of trial and error. Under teacher guidance, they carried out bacterial culturing, titration, and bacterial growth monitoring to ensure the cleaner was genuinely effective.
One of the biggest technical challenges was ensuring the powder wouldn’t clog the spray bottles, which they distributed alongside the product. After multiple failed attempts, the team designed a custom mesh filter inside the pump, a small but critical innovation that allowed the product to function reliably.
“Innovation doesn’t succeed on the first try,” Kayleen reflected. “That process taught me patience and problem-solving.”
Learning from the community — and listening closely
Community feedback played a central role in refining Nusantara Bersih.
The team distributed their first 50 kits to a local village, using the opportunity to ask questions, listen, and adjust.
Residents shared detailed feedback on everything from fragrance and tablet size to cleaning ratios and the clarity of the instructions. The original version had a strong, slightly bitter scent, so the team developed a lime-infused alternative that felt fresher and more familiar. They also refined the tablet ratios for different cleaning uses and rewrote the instruction manuals to be more direct and easier to follow.
They also began teaching communities how to make the product themselves, reinforcing long-term sustainability and local ownership.
SDGs in action
While Nusantara Bersih initially focused on SDG 6 (Clean Water and Sanitation), the team quickly realised their work touched several goals at once. Improving household hygiene supported SDG 3 (Good Health and Wellbeing), while the reusable kits and biodegradable materials aligned with SDG 12 (Responsible Consumption and Production). By reducing plastic waste and transport emissions, the project also contributed to SDG 13 (Climate Action). Rather than treating the SDGs as separate checkboxes, the project reflects how these goals intersect in real life.
Meet the team
Ashley
Ashley describes herself as “a good balance between calm and fun.” She values quality time with friends and family, loves playing padel and tennis, and is always excited by travel, especially when it involves discovering new food.
During Nusantara Bersih, she found herself tested by uncertainty.
“There was always a question of whether people would trust the tablet compared to commercial products. But instead of freezing, I focused on improving the product and learning from feedback.”
That experience reshaped how she sees her own resilience.
“Visiting nursing homes and underprivileged areas changed the way I see my own privileges. It pushed me from noticing problems to wanting to act.”
Looking ahead, Ashley is curious about the intersection of science and business, and hopes to grow into someone who can create meaningful, practical impact.
Kayleen
Kayleen admits she can come across as serious at first, but beneath that is a deeply cheerful, ambitious person with a visionary mindset. Raised to aim high, she is always searching for opportunities to grow.
Outside of school, she loves discovering new restaurants, watching movies, and spending intentional time with people she cares about.
Technically, Nusantara Bersih stretched her patience.
“The Lerak tablet didn’t work at first. It clogged pumps, the suspension wasn’t right, and it was frustrating.”
But persistence paid off.
“We kept troubleshooting until we created a solution. That taught me innovation doesn’t come instantly, and that I can stick with difficult problems.”
Serafina
Serafina comes across as curious and hardworking, always eager to learn and challenge herself. When she’s not studying, she enjoys playing the piano and participating in clubs and competitions.
One experience stands out most strongly for her.
“Visiting a local school in Banten was eye-opening. The limited resources made me realise how many people need support but never truly receive it.”
That moment strengthened her motivation to engage more deeply with communities and reminded her why service, when done thoughtfully, matters.
Advice for future CAS students
When asked what advice they would give to future CAS Project Challenge participants, the team didn’t hesitate:
“Open your eyes to the community around you. Observe. There are problems we take for granted every day, gaps that already exist, and that’s where meaningful projects begin.”
Nusantara Bersih is not about a perfect solution or a polished product. It’s about students who noticed something that wasn’t right, took responsibility, and stayed curious enough to keep refining their work.
It shows what CAS can be when students are trusted to think deeply, work collaboratively, and engage respectfully with real communities.
We are proud to name Serafina, Kayleen, and Ashley as the winners of this year’s CAS Project Challenge, and even more excited to see where their curiosity, compassion, and creativity take them next!
