Draining shower water is caught, filtered, and UV-disinfected in real time (multiple times per minute) and immediately recirculated through the showerhead, topped up with only a small trickle of fresh water, roughly 90% less water and 80% less energy than a standard shower of the same length, per the manufacturer's own published figures (independent verification not yet checked), since most of the recirculated water is already hot. The clear performance benchmark for this sub-function, ahead of the plain pressurised shower. Trade-off: a real-time filtration/UV/pump/control system is exactly the kind of proprietary, specialist-repair-only mechanism this catalog flags elsewhere, a failure here means no shower at all, not just a less efficient one.
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.