Water Treatment Using Sedimentation and UV lights

Access to safe drinking water is a basic human right, yet it remains an ongoing challenge for many Indigenous and remote communities across Canada. Learning that some communities have faced long-term drinking water advisories for years challenged our assumptions about equity in a developed country and motivated us to take action through science.

We designed this project to explore whether a simple, low-cost water treatment system could offer a practical solution. Inspired by both real-world need and scientific curiosity, we investigated the effectiveness of combining sedimentation and ultraviolet (UV) light—two proven methods that are accessible, chemical-free, and scalable. Our central question was: Can a two-stage, affordable system significantly improve water quality to safer levels?

This project is important because it focuses on accessibility and sustainability. Many existing water treatment systems require expensive infrastructure and technical expertise, which can be difficult to implement in remote settings. In contrast, our approach is designed to be simple, energy-efficient, and adaptable, making it more realistic for communities with limited resources.

The potential impact extends beyond our experiment. A system like this could reduce exposure to harmful bacteria, improve daily living conditions, and decrease reliance on costly bottled water. More importantly, it highlights how science and innovation can be used to address real-world inequalities.

We undertook this project not only to test a hypothesis, but to contribute toward a future where access to clean water is reliable, equitable, and sustainable for all.

Our research began by exploring both scientific sources and traditional Indigenous knowledge about water. Indigenous communities have long understood water as a sacred resource requiring careful stewardship — this value guided our entire project. We combined that wisdom with modern science to investigate how sedimentation and UV light can purify water.

Experiment Setup

We collected approximately 2 litres of water from a community water source — reflecting the Indigenous principle that water belongs to everyone and must be protected. We divided it equally into four 500 mL labelled containers, each receiving a different treatment: no treatment (control), sedimentation only, UV light only, and a combination of both.

Treatment Process

Sedimentation mirrors a natural process Indigenous peoples have observed for generations — allowing particles to settle by letting water rest undisturbed for 60 minutes before carefully pouring off the cleaner top layer. UV treatment used a submerged wand for 30 minutes to reduce bacteria. The combined sample received sedimentation first, then UV treatment.

Measuring Results

Before and after each treatment, we measured water clarity using a turbidity meter (NTU) and collected 1 mL samples using sterile pipettes for agar plating. Plates incubated at 22°C for 48 hours before we counted bacterial colonies.

Ensuring Accuracy

We repeated the full experiment three times, then calculated averages and percent reductions to ensure reliable results.

Model Design

We built a physical filtration model to demonstrate the purification steps visually — showing how both traditional observation of nature and modern science point toward the same goal: clean, safe water for all communities.

By honoring both knowledge systems, our experiment recognized that protecting water is not just a scientific responsibility — it is a human and cultural one.

Indigenous teachings remind us that water is life — Nibi Manidoo in Anishinaabe tradition. Our results showed that by combining both traditional understanding of natural filtration and modern science, clean water is achievable even with simple materials.

How Our Prototype Works

We built a gravity-fed filtration column inspired by how the earth itself filters water naturally — a process Indigenous peoples have observed and respected for thousands of years. Our model used six layers:

Gravel — traps large particles

Coarse sand — filters medium particles

Fine sand — captures fine particles

Activated charcoal — absorbs chemicals and odors

Cotton — acts as a final barrier

This layered approach mirrors nature's own filtration system found in riverbeds and soil — systems Indigenous communities have long relied upon for clean water access.

Our design also featured a dual-storage system: Tank 1 stores filtered water for everyday use like washing, while Tank 2 stores UV-purified water safe for drinking. The UV light only activates when Tank 2 runs low, making the system energy-efficient and practical for communities with limited resources.

Main Results

Our prototype showed consistent and measurable improvement across all three trials. Water clarity improved significantly after passing through the filtration column, and bacterial counts dropped considerably after UV treatment. The combined method — sedimentation, physical filtration, and UV — produced the cleanest results overall.

While small variations existed between trials, these were minimal and linked to minor external factors like slight timing differences or environmental conditions during testing. The overall trend remained stable, which strengthens confidence in our findings.

Importantly, refinements we made between design iterations — adjusting layer thickness and UV exposure time — led to noticeable performance improvements, showing that testing and reflection are essential parts of good design.

Analysis

We used averages across three trials to summarize our data, giving a more accurate picture of true performance rather than relying on a single result. Graphs comparing turbidity (NTU) and bacterial colony counts before and after each treatment clearly showed the step-by-step improvement our system achieved.

We chose these statistical methods because they are simple, reliable, and honest — values that align with both good science and Indigenous principles of transparency and responsibility toward community wellbeing.

What This Means

Our results demonstrate that a low-cost, gravity-fed filtration system combining natural layered filtration and UV purification can meaningfully improve water quality. This matters deeply for Indigenous and remote communities that continue to face unsafe water conditions — communities that have always known water deserves protection.

Science confirmed what Indigenous knowledge has always taught: working with nature, rather than against it, produces the best results.

Water is life — a truth Indigenous peoples have honored since time immemorial. Our results matter because they show that clean water is achievable using simple, low-cost methods, offering real hope for Indigenous and remote communities that continue to face unsafe drinking water conditions.

What We Can Conclude

Our prototype successfully addressed the problem we set out to solve. The combined method — natural sedimentation, layered filtration, and UV purification — produced the greatest improvement in both water clarity and bacterial reduction. This mirrors what Indigenous knowledge has long understood: working in layers, respecting natural processes, and using only what is needed leads to the best outcomes.

The consistent results across three trials confirm our design is stable and reliable — not a one-time outcome, but a repeatable solution. Small refinements between iterations also led to meaningful improvements, proving that careful observation and adaptation — core values in both science and Indigenous ways of knowing — make solutions stronger.

What We Learned

We learned that no solution is perfect on the first attempt. Like the generations of Indigenous water keepers who observed, adapted, and passed knowledge forward, we too had to test, reflect, and improve. Data-driven decisions, not assumptions, guided us toward better results.

Looking Forward

With more time and resources, this prototype could be refined and scaled for real community use. Our results give us confidence that affordable, nature-inspired water purification is not just possible — it is necessary, and it is our responsibility.

To improve our prototype, we would use more precise tools to reduce experimental error and refine the design to be more durable and user-friendly. Further research would test how the system performs across a wider range of real-world conditions and at larger scales.

Most importantly, our next step would be bringing this prototype directly into Indigenous and remote communities — gathering real feedback from the people who need clean water most. Their voices, lived experience, and traditional knowledge would guide every final improvement. Real change starts with listening to the community.

We are sincerely grateful to everyone who helped make this project possible.

Thank you to our teacher for guiding us in refining our research question and providing thoughtful feedback at every stage — your direction shaped the foundation of this project. We also thank those who helped us access the materials and equipment needed to build and test our prototype. Without your support, our experiments would not have been possible.

To everyone who assisted during our design and testing phase — your suggestions helped us spot weaknesses and build a stronger, more reliable prototype with each iteration. We are also grateful to those who helped us analyze and present our results clearly and confidently.

Most importantly, we honor the Indigenous communities whose sacred relationship with water — Nibi Manidoo — inspired the heart of everything we built. Their knowledge reminded us that science is most powerful when it serves people.

Ekosi— Thank you all.

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