Treatment / filtration

Ranked by effluent quality, how clean the water is at the outlet, and how consistently. Membrane filtration is the ceiling and the only option producing water fit for indoor non-potable reuse; the biological beds reach a good standard given enough area and residence time; a sand filter alone is a pretreatment stage, not full treatment. Drain water heat recovery appears in this sub-function but is not ranked. It recovers heat and does not treat the water at all.

Solutions

• Constructed wetland / reed bed filtration: Plants and gravel media biologically filter greywater; low-tech, no powered parts in the bed itself. Gravity-fed and genuinely passive where the site gives enou
• Sand filter: Simple mechanical filtration stage, often paired with a wetland or as a standalone pretreatment. Gravity-fed and genuinely passive where the site gives enough f
• Greywater heat recovery (drain water heat exchanger): Passive heat exchanger around a shower/sink drain preheats incoming cold water using outgoing warm greywater, no pump, feeds directly into domestic water heatin
• Membrane bioreactor (MBR) greywater recycling package unit: Combines biological treatment with membrane filtration in one packaged unit, producing consistently high-quality reclaimed water suitable for indoor non-potable
• Wood-chip filter (Filtres a Broyat de Bois, FBB): Biological filter bed of wood chips, developed and tested specifically for treating greywater alone (as distinct from constructed wetlands typically sized for c