Malaysian students have built a prototype that attempts to recover electricity from one of the most overlooked sources of wasted energy in a home, water flowing down the sink. Developed by three students at Universiti Malaya, WattsUp is an IoT-enabled micro-hydropower system designed specifically for the weak and intermittent flow produced by household wastewater. Rather than allowing the water to immediately disappear down the drain, the system filters and temporarily stores it before releasing it through a nozzle at higher speed. The resulting water jet drives a small Pelton turbine connected to a generator. The students developed the concept because conventional hydropower systems generally depend on larger and more continuous flows, whereas household wastewater arrives in short bursts. Their prototype explores whether those small, otherwise wasted flows can be converted into useful electrical energy.
How Malaysian students are recovering energy from wastewater
The basic principle behind WattsUp is micro-hydropower, where moving water is used to create mechanical motion and that motion is converted into electricity. What makes household wastewater difficult to harness is its irregular nature. Water may flow from a sink for a few seconds while someone washes their hands or dishes, then stop completely. The Malaysian students therefore designed WattsUp around accumulation rather than continuous generation. Wastewater first passes through a multi-stage filter before entering a 2-litre storage tank. Once enough water has accumulated, a bell siphon automatically releases it, sending the water through a converging nozzle and towards the turbine. The system consequently turns a relatively weak and intermittent wastewater stream into a short, more concentrated discharge capable of driving the turbine. Research into wastewater energy recovery supports the broader principle behind the project. Studies have investigated micro-hydropower at wastewater treatment facilities and in buildings, although those systems operate at substantially larger scales than WattsUp.
A bell siphon gives the stored water a sudden burst
The bell siphon is central to the students’ solution because it allows the system to release accumulated water without relying on an electrically powered pump. As the tank fills, water reaches the level needed to trigger the siphon. The stored water then flows out through the system, producing the discharge needed to drive the turbine. This approach addresses one of the fundamental problems of trying to harvest energy directly from a domestic drain. A small trickle may not contain enough useful hydraulic energy to keep a turbine turning, but accumulating several small wastewater events and releasing the water together creates a more concentrated flow. The students tested several versions of the mechanism and redesigned the siphon tank because relatively small changes in its dimensions affected whether it would activate reliably at low incoming flow rates. The final design uses an acrylic tank and is intended to fit within the limited space normally available beneath a sink.
The tiny turbine went through several redesigns
WattsUp uses a Pelton turbine, an impulse turbine normally associated with high-head water systems. The students considered other turbine configurations, including Crossflow and Turgo designs, before selecting a Pelton arrangement for the concentrated water jet produced after the siphon activates. Their development process involved several physical prototypes. An early version used a 16-bucket turbine runner, but its greater mass created more rotational inertia and made it harder for the turbine to start quickly. The students subsequently developed a lighter 12-bucket runner, changing the hub thickness and bucket geometry to improve its behaviour. The turbine is coupled to a permanent-magnet DC generator, allowing the rotation produced by the water jet to be converted into electrical output. The project documentation describes further optimisation of the turbine blades and generator coupling as a future step, which means the current system should be regarded as an experimental prototype rather than a finished household power appliance.
Sensors allow the system to monitor its own performance
The invention also incorporates an IoT monitoring system rather than functioning solely as a mechanical device. An ESP32 controller monitors parameters including water level, voltage, current, flow rate and battery status, with information made available through a web dashboard. The students also incorporated maintenance notifications and emergency alerts, while an emergency water outlet is intended to provide a route for water if the system becomes blocked. The design was developed around the physical constraints of an under-sink installation and includes adjustable head piping to accommodate different sink configurations. According to the project’s James Dyson Award documentation, the prototype costs approximately RM350, while the students hope to reduce manufacturing costs below RM200 through further material and design optimisation. Their stated future work includes increasing electrical output, improving the casing and making installation and maintenance easier.
WattsUp is a prototype, not yet a household power station
The idea of recovering energy from wastewater is scientifically plausible, but the scale of the available energy matters. Research into wastewater hydropower has shown that larger buildings and treatment facilities can recover useful electricity because they handle much greater volumes of water and often have significant differences in elevation. One peer-reviewed study examining wastewater energy recovery in buildings found that the potential increases with building size and water flow, while other research has explored variable-flow micro-hydropower at wastewater treatment facilities. Those findings cannot be directly applied to a kitchen sink, where the available water volume and hydraulic head are much smaller. WattsUp’s own project documentation therefore points towards further development rather than claiming that the device can supply significant household electricity today. Its significance lies in the engineering approach: instead of trying to extract energy from every weak trickle, it stores intermittent wastewater, releases it through a passive siphon and uses the resulting water jet to drive a small turbine. If the students can improve its efficiency and keep manufacturing and maintenance costs low, the concept could offer a way of recovering at least some energy from a waste stream that homes normally send straight into the drainage system.
