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Water·applied

Greywater Recycling

Why it matters

The water leaving a shower, a basin, or a washing machine is "grey", as opposed to the blackwater that carries sewage. It is barely dirty: warm, lightly soaped, easy work for a filter and a UV lamp. Yet the standard plumbing of civilization mixes it with sewage and throws it away, then flushes toilets with water treated to drinking standard. Meanwhile flushing alone is about 30% of a home's indoor use — the largest single consumer, ahead of showers and far ahead of baths. Recycled water does that job just as well. Every litre used twice spares the system one round of collection, storage, and treatment. Recycling therefore shrinks every other component of the water system at once: smaller tanks, smaller filters, longer reserves when the rain is late or the grid is down. And there is a pleasure argument nobody expects from plumbing: a shower that cleans and recirculates its own water in real time removes the oldest tension of off-grid life — the one between a long hot shower and a finite tank.

Role in 001's holistic picture

Recycling is the demand side of the Water Innovation Model: it multiplies storage without digging and shrinks treatment load at the source. Together with waterless toilets it forms the pair of great demand-cutters. Next to it lies sanitation, where treated effluent finds its second life on the land. The demand side as a whole serves Water Autonomy.

In the world

The Dutch company Hydraloop turned that logic into a product: a cabinet-sized unit that treats shower, bath, and laundry water for reuse in toilets, washing machines, and the garden. That cuts a household's mains-water and sewage load by around 45% (per Hydraloop). The market has ranked it highly: the system took the overall "Best of the Best" award at CES 2020 against more than 20,000 products, and a UN WIPO Global Award in 2022. That is about as clear a signal as exists that closed-loop water at household scale has crossed into the mainstream.

The same logic scales up to cities. Singapore — an island with no natural aquifers — named its purified wastewater NEWater and made it a strategic resource. Five plants push water through microfiltration, reverse osmosis, and UV to beyond-drinking-standard purity. Its largest drinkers are semiconductor fabs, which demand ultrapure water. Together the plants cover about 40% of national demand, with a 55% target by 2060. And Windhoek, Namibia, has been returning treated wastewater straight into its drinking supply since 1968 — the world's longest-running direct potable reuse. Water used twice became ordinary long ago. The exotic thing now is a city that still throws it away after one use.

How 001 engages with it

We have built and run the most radical version: ShowerLoop, a real-time recycling shower with filtration and UV in a closed loop. It follows an openly published design, and 001 deployed it at Burning Man in 2023, about as harsh a water-scarcity test as exists. At House 001, by contrast, everyday reuse is deliberately minimal and exact. Water rejected by the drinking-water reverse-osmosis filter returns to the IBC tank that supplies the whole house. Those losses become reserve. Shower and kitchen greywater goes straight to the soil through a crushed-stone bed beneath the house. The Hlibivka design integrates a Hydraloop-class unit. That recycling is what lets the design halve its rainwater storage volume. In the published Tepla Gora strategy, the recycling questions are drawn precisely: greywater collected near the building is the practical candidate for toilet flushing, while returning septic effluent indoors stays an open question until its quality is confirmed. Meanwhile surplus treated effluent goes to fertigation, and that path is certain. On the treatment side, the community has already moved on its own: the Tepla Gora team designed and built a bioplato — a constructed wetland — by itself, with no 001 involvement. It treats the greywater of the 30-person hostel and returns it to the natural cycle. That is treatment, not yet reuse. The loop back into the building remains the open design question the strategy drew.

Maturity: applied. ShowerLoop built and field-deployed; whole-house recycling designed at Hlibivka; at Tepla Gora the community's own bioplato already treats the hostel's greywater, while the reuse loop stays a live design question.

Further reading