Direct greywater diversion to toilet flushing

Shower or bath water diverted straight to the toilet cistern or bowl by gravity or a simple bucket, with no treatment beyond settling, the lowest-tech greywater reuse technique in this catalog. Same-day use only, since untreated greywater develops odor and bacterial growth within hours to a day or two of storage.

Cost
Low
Upkeep
None
Skill to build
None
Lifespan
Matches plumbing/diversion-valve lifespan, 20-30 years for simple gravity diversion hardware
Embodied carbon
Low
Space / material use
Low
Output timing
On-demand/controllable
Skill to repair
None
Regulation (FR example)
Greywater reuse is permitted under decret 2024-796 and the arrete of 12 July 2024, on an experimental basis until 31 December 2034, for laundry, indoor floor washing and vegetable-garden watering. Not permitted for drinking, cooking or bathing.

Note: Cost, carbon and footprint are rated against the other options for this same need, not in absolute terms.

Inputs

Outputs

none

Sources

What this page does not tell you

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.