Start by walking your local river and marking the spots where trash tends to collect, such as confluences where two streams meet, sharp bends, bridges and weirs. Pick one or two bottleneck sections that your team can reach safely and regularly. Next, contact your local council or river authority to explain the project and agree permission to release devices; the playbook includes ready-made coordination forms to make this conversation easier. Then recruit your observation team of up to 10 people, mixing local residents with students. Agree a lead coordinator, a regular meeting point and a shared group chat so everyone knows the plan for each session.

Gather your team for a making session and assemble one drifter per participant from the kit. Clean and dry recycled plastic bottles, fit the open-source electronics and cellular module inside, and seal every joint with waterproof tape. Follow the blueprints step by step and check each device against the parts list. Before you go near the river, run a float test in a bucket or bath to confirm each drifter sits upright and stays watertight. Switch on the cellular module, check that each device appears on the data platform, and give every drifter a clear name or number so you can track and recover it easily.

Safety comes before science, so hold a waterside safety briefing before your first release. Fit everyone with life jackets and non-slip shoe covers, bring rain gear and a first-aid kit, and agree clear rules about how close people may stand to the water. Then run a full rehearsal at your chosen site. Assign roles for each session: a releaser, a spotter who follows the drifter, a recoverer with the telescopic net, and a recorder who logs times and notes. Practise retrieving a drifter from the water with the net and hooks until every recoverer feels confident. Never send anyone into the river itself.

Run six observation sessions over three months on agreed days. At each session, release your drifters at the upstream point, follow their paths on the live map and note where they slow down, circle or stop. Your recorder logs the weather, water level and any trash you spot along the route. When the session ends, recover every single device, count them back in and pack them in waterproof bags; full recovery keeps the project from adding new litter to the river. If heavy rain arrives, consider an extra session, since storms show trash movement at its most dramatic. Finish each outing with refreshments and a quick team debrief.

Once your sessions finish, upload and check your data on the platform so it joins the shared river bottleneck map. Look together at where your drifters stalled and for how long, then turn those findings into simple, practical recommendations, such as new bins, targeted clean-up days or litter traps at the worst hotspots. Present your map to your local council, schools and community groups, and invite local media to see the results. Celebrate your team’s work with a short showcase event. Finally, share your experience with other communities and use the replication playbook to help them open their own river-monitoring point further along the network.