Passive solar throughput (~10 L/m²/day) means collector area scales directly with population served

Solar evaporation yields ~10 L/m²/day outdoors—near the physical ceiling, not an engineering gap. Full domestic use (~50–100 L/person/day) requires 5–10 m² per person; a 10,000-person town needs 5–10 hectares. This bounds the technology to household/hamlet scale, not municipal su