DIY Off-Grid Greywater: Murray's Tiny House Micro-Wetland

This practical guide documents Murray's off-grid DIY greywater treatment system for a tiny house on wheels in the Yarra Valley, Victoria, Australia, designed on permaculture principles of biomimicry to create a micro-wetland for treating non-toilet wastewater before irrigation. Greywater—household water from sinks, showers, and laundry—is diverted into a multi-basin treatment setup mimicking natural wetland filtration. The system features sequential gravel basins separated by wooden dividers lined with plastic, forcing water to flow through layered media: coarse gravel for settling, finer substrates with plants for biological breakdown, achieving pathogen and nutrient removal without chemicals or power. Treated effluent then feeds wicking garden beds for food production, stacking water reuse with permaculture productivity. Construction details include a primary settling chamber to trap solids, followed by two treatment basins (each 1m x 0.5m x 0.5m deep) filled with 20-50mm gravel and wetland plants like reeds or rushes for root-zone aeration and microbial activity. Water enters via a 50mm pipe, percolates horizontally, and exits clarified for subsurface dripline delivery under mulch, contacting the soil food web for final polishing. Affordability is key: built from recycled materials (old baths, gravel, scrap wood) for under $200 AUD, DIY in a weekend. Performance metrics from observation: clear output water suitable for edibles after 24-hour retention, no odors, and thriving wicking beds yielding veggies year-round. Integration tips: position downhill from house for gravity flow; oversize basins 20% for surges; harvest plant biomass annually for mulch. Challenges addressed: grease trapping via preclearer; winter slowdown mitigated by insulation. This system excels for mobile or small-scale off-grid setups, reducing water demand by 40-60% while building soil fertility. Practitioners learn concrete steps for zoning (Zone 1 treatment near dwelling), material sourcing, plant selection (e.g., Phragmites for high BOD removal), and scaling to larger homesteads by paralleling units. It exemplifies regenerative water management, turning waste into resource with measurable ecosystem services.