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National Runner Up

Rinse Repeat

Rinse Repeat is a compact home wastewater recycling system that halves water use in front loading washing machines.

  • In-context CAD visualisation of Rinse Repeat.

  • Video explaining the context and function of Rinse Repeat.

    Video explaining the context and function of Rinse Repeat.

  • Wastewater treatment results from the working prototype.

  • How Rinse Repeat works.

  • Overview of the working prototype and its accompanying CAD visualisation.

  • Key stages of the design process.

What it does

Rinse Repeat is a compact home wastewater recycling system that halves water use in front loading washing machines. By treating half the wastewater produced in a load of washing then resupplying it in the next load, Rinse Repeat saves 7800L of water/home/year.

Your inspiration

Born into the Millennium Drought in regional Australia, water scarcity is always on my mind. Installing home wastewater recycling systems is a key way Australia will respond to a water scarce future but current offerings are large, complex and expensive. This prompted me to explore scenarios in the home where a compact system focused on usability could make wastewater recycling an accessible practice. Washing machines presented an ideal context as their water inlet/outlet hoses can be easily accessed and rerouted by users. I subsequently asked ‘is it possible to extract and treat washing machine wastewater then recycle it in the next load?’

How it works

1-CONNECTION: Rinse Repeat is connected to inlets/outlets of an existing washing machine. 2-CATEGORISATION: Wastewater flows from washing machine into Rinse Repeat where a sensor reads pollution. As the washer moves from washing to rinsing, the pollution level of the wastewater drops exponentially. 3-EXTRACTION: Rinse Repeat sends wastewater to the laundry drain until it detects a pollution drop. Here, the less polluted wastewater (roughly 50% of total wastewater) is diverted to the treatment tank. 4-TREATMENT: A treatment fluid (aluminum sulphate, chlorine, water) is mixed into the wastewater to enable treatment via coagulation/flocculation. By only treating the cleanest half of the total wastewater, high efficiency treatment is achieved in a compact object. 5-RECYCLING: When the washer is used next, treated water then tap water are supplied. 6-WATER SAVING: 50% saved/load totaling 7800L saved/year. This represents a 5% reduction in yearly home water use.

Design process

A literature review led to the conclusion that a small wastewater recycling system (capable of easily and affordably connecting to an existing point in the home) was key to removing entry barriers to home wastewater recycling. Washing machines were thus selected as an intervention point due to their easily reroutable water inlets/outlets. Initial contextual research helped frame the project and involved documenting wastewater properties, interviewing stakeholders and disassembling a washing machine. The first treatment enabled prototypes used natural treatment processes (activated charcoal filters, slow sand filters, vegetated biofilters) but were abandoned due to their poor size to efficiency ratio. Subsequent prototypes centering around chemical treatment produced stronger results but had consistency issues. A breakthrough came with the addition of the categorisation/extraction system. Extracting only the cleanest wastewater meant the treatment process was faster, required less chemical input and was a more compact size. Comparison of prototype results against Government standards conditionally validated the treated water as suitable for recycling. Finally, spatially surveying 54 home laundries combined with user experience mapping led to visualisations of the proposed form.

How it is different

Current home wastewater recycling systems are inaccessible to householders because they are very large, complex and costly (averaging $10K). The reason for this is twofold. (1) These systems don’t distinguish between wastewater sources. Thus, a multi-process ‘blanket’ approach to wastewater treatment is used. (2) To install them, severe alterations to household plumbing are required. Rinse Repeat challenges this by framing wastewater recycling in the context of a simple home appliance. By only targeting the cleanest half of one specific wastewater source, Rinse Repeat can achieve efficient treatment with minimal processes whilst remaining highly compact. Additionally, because Rinse Repeat is designed with a ‘plug and play’ focus it can be installed quickly and without the need to alter existing plumbing. By overcoming traditional entry barriers, Rinse Repeat dramatically improves the accessibility and feasibility of widespread home wastewater recycling.

Future plans

Before market entry, wastewater treatment/recycling systems in Australia are required to undergo long term testing and documentation. This will continue to be undertaken alongside prototype refinements in order to receive Government certification. From a manufacturing standpoint, Rinse Repeat is made of repurposed washing machine components (valves, pumps, sensors) meaning it could utilize existing supply chains. Water conservation is something I’m incredibly passionate about. Rinse Repeat is not my first foray into this area, neither will it be my last. We face enormous future pressures around water and I want to be part of the solution.


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