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Water·applied

Water Treatment

Why it matters

Unsafe water remains one of the largest health burdens on the planet. The industrial answer is to chlorinate everything at a central plant and pump it everywhere. That approach treats every litre as if it were destined for a drinking glass, then spends it flushing toilets. Autonomous treatment inverts the logic: quality is matched to use. The expensive chemistry then applies to litres per day instead of cubic metres. Done right, an off-grid home drinks water cleaner than most cities deliver, without a gram of chlorine, from equipment that fits in a cupboard. That inversion is what makes water autonomy affordable at all. It is also where an autonomous building earns the "healthier than the grid" claim. Household-scale biological treatment already does this at scale. The biosand filter is a cupboard-sized slow-sand filter with a living biological layer, spread worldwide by CAWST. These filters are in use in over 200,000 homes, and field studies in Ghana measured about 60% fewer diarrhea episodes in filter households. Clean water from a living filter, at the scale of a single sink, with the health outcome measured rather than assumed.

Role in 001's holistic picture

Treatment is the refinery between storage and the tap. The economics of the entire water organism are decided here: how the tiers are drawn determines how much collection and storage the site needs in the first place. It also guards the boundary that our pond research drew — which water may enter the house, and which stays on the land. The same tiering decides what happens to water on the way out, too: greywater cleaned to technical grade returns to irrigation instead of the drain.

The quality tiers

Designing by quality, not by source. Tier A, drinking and cooking: the full chain — first flush diversion, sealed dark storage, fine mechanical filtration, activated carbon, UV disinfection, reverse osmosis where needed. That chain serves a tiny volume: a household of four drinks and cooks with about 10–15 litres a day. Periodic lab tests verify the result. Tier B, household: sinks and laundry need pathogen-free, low-turbidity water, and drinking-grade is surplus here. Basic filtration plus disinfection suffices. Showers sit wherever the owner draws the line: Tier B is sufficient, and Tier A remains a legitimate comfort choice. The Hlibivka design put drinking-grade water even in the shower. Tier C, technical: irrigation, cleaning, fire reserve take screening only. Two physical facts drive the design: turbidity is UV's enemy (particles shield microbes from the light), and Ukrainian drinking standards (DSanPiN 2.2.4-171-10) demand under 1.0 NTU with zero E. coli. Those numbers stay beyond the steady reach of an open pond, which is why pond water belongs to the technical tier. Whether a site should pipe that water to the house at all is a separate question each design must answer. Our pond page holds ours, and it is still open.

How 001 engages with it

The living lab runs active treatment experiments: since 2025, House 001 has been testing aerators and MBBR biological filtration as part of its water program. Some experiments fail, and we publish those too. A series of attempts to clean organic acids out of the harvested rainwater failed. The lesson: when treatment keeps fighting the source, the fix belongs upstream. House 001's roof is now being upgraded accordingly. At Tepla Gora, the published strategy separates a small drinking-grade path (roof rainwater through the full chain) from household and technical tiers. That structure was sharpened by our most useful negative result, the pond-water study. It concluded that an open clay pond is a surface water body by contamination profile, needs a mini treatment plant to reach household grade, and therefore stays exactly where it is useful, in Tier C. The Hlibivka design specifies the full drinking chain: 1–5 µm mechanical filtration, carbon treatment, a 600 L/h UV stage, and 200 L/h reverse osmosis.

Maturity: applied. Treatment chains operate at Tepla Gora and are under active component testing at House 001; the tiered design is our published working method.

Further reading