A two-bucket system: an inner perforated bucket holds the laundry, a plunger sealed with a bicycle inner tube forces water through it by hand-pumping, cheaper and mechanically simpler than the pedal-powered washing machine (no drivetrain or pedal mechanism at all), at the cost of more direct manual effort per load. Works with potable or non-potable water.
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.