When we realised clean water was slipping down our drains, we asked: what if “used” water became a resource? Grey for Good is our answer - an automatic home system that captures greywater from air-conditioners, dehumidifiers, showers, and sinks, then filters it for safe second uses like flushing, cleaning, and watering plants.
Our goal is to produce a compact, automated collection and treatment system that fits into everyday routines, reduces household water waste, and lowers utility costs without sacrificing safety or convenience. By guiding each drop through targeted filtration and reuse, we turn an overlooked byproduct into a dependable resource for homes and schools. This is a scalable solution with immediate, measurable impact - and a clear invitation for you to help bring smarter water use to more families, one household at a time.
Inspiration came from
Our inspiration came from everyday moments: watching AC units drip, showers run, and sinks swirl away perfectly usable water. A lesson on the water cycle and a "virtual visit" to the filtration plant made it clear - clean water takes energy, infrastructure, and care. We realised that if we could safely reuse greywater at home, we could cut waste at the source and make conservation practical for every family. That spark became Grey for Good.
What social problems do you solve?
We tackle water waste and access by turning household greywater into a reusable resource. Grey for Good directly advances SDG 6 (Clean Water and Sanitation) by increasing water-use efficiency and reuse, and supports SDG 12 (Responsible Consumption and Production) through smarter resource cycles at home. By lowering water demand - and, in many regions, the energy used to pump and treat it - we also contribute to SDG 13 (Climate Action). Our system helps families reduce bills, builds resilience to droughts, and empowers students and communities to practise everyday conservation.
How do we start from 0 to 1
Before honing in on household greywater, we explored the bigger picture - studying the water cycle, virtually touring filtration plants, and learning how cities clean and move water. Then we brought the lesson home. We began by mapping where greywater appears in a typical house, timing taps and measuring drip rates with kitchen scales and measuring cups. We sketched simple flow diagrams, and compared filter media (sand, activated carbon, and mesh) with basic water tests for clarity and odour. From there, we aim to build a gravity-fed prototype from recycled bottles and tubing. We look to add a small pump with check valves and overflow safeguards, and iterated to reduce noise, cost, and clogging - moving step by step toward a quiet, safe, easy-to-maintain design.
The challenge we encountered
- Standing out: water-saving is widely discussed, so we had to deliver true innovation - automatic, low-noise, compact, and user-friendly.
- Practicality: designing a system that’s safe, affordable, and easy to install/maintain at home.
- Quality control: ensuring reliable filtration, preventing odours and clogs, and managing variable flow.
- Compliance: learning about plumbing codes, backflow prevention, and safe reuse guidelines.
- Behaviour change: making adoption effortless so families actually use it.
The resources we needed
- Materials: food-safe tubing, fittings, check valves, small pump, flow sensors, filters (sediment, carbon), housing, overflow safeguards, containers, test kits.
- Tools: basic hand tools, drill, cutters, sealant, 3D printer access for custom parts, multimeter.
- Expertise: advice from a plumber, environmental science teacher, and local water utility on codes and safe reuse.
- Testing: simple lab access for water quality (turbidity, pH, conductivity, microbes) and a safe test rig.
Who are we?
We are a local Primary 5 class with big ideas and busy hands. United by the motto “Dream water, dream change,” we’re learning by doing - researching, prototyping, and sharing solutions that make everyday conservation real for our community.
