Keeps sink/shower/laundry water in its own line so it can be treated and reused independently.
Cost
Medium
Upkeep
None
Lifespan
Matches plumbing pipe lifespan (30-50+ years); this is a routing/design choice, not a separate material
Embodied carbon
Low
Space / material use
Low
Output timing
Continuous process
Skill to repair
Basic
Regulation (FR example)
On-site sanitation (assainissement non collectif): the installation must be declared to and approved by the local SPANC before work starts, and is subject to periodic inspection. Arrete du 7 septembre 2009 modifie.
Note: Cost, carbon and footprint are rated against the other options for this same need, not in absolute terms.
No sizing or quantities: how much a technique yields, and how much a household needs, both depend on the build and the people, so the catalogue compares options rather than dimensioning them. It carries no bill of materials and no build sequence, and it is written for an oceanic, clay-soil climate (Normandy, France). Regulatory notes are indicative and need confirming locally.