Water consumption competes with supply exactly where the cooling works best

The problem

Evaporative cooling works by turning liquid water into vapour — water consumption is not a side effect, it is the mechanism. A single bloc° unit consumes about 56 litres on a day above 30 °C; an array scales that linearly. The problem is the overlap of two maps: hot-dry climates where evaporative cooling performs best are very often the same water-stressed regions where every litre is already contested between drinking supply, agriculture, and sanitation. The technology is thirstiest exactly where water is scarcest.

bloc°'s funnel roof harvests rainwater, but its own figures show the balance doesn't close: ~24 L/day harvested against ~56 L/day consumed on hot days. The shortfall must come from mains water or another source — and hot, dry spells are precisely when rain is absent and mains demand peaks.

Why it matters for deployment

• A cooling intervention that draws potable water during a drought-coincident heatwave can be a net harm in a water-stressed city.
• Per-unit numbers look small; a deployed network's aggregate draw across a summer does not, and that is the figure that belongs in a procurement decision.
• It interacts with the humidity constraint: the drier the air (best cooling), the higher the evaporation rate (most water used).

What a resolution needs

• A non-potable feed as the default design assumption: rainwater capture sized realistically, greywater, or recycled/HVAC condensate — not the drinking-water main.
• A published per-unit and per-network seasonal water budget stated against local water availability, so the trade-off is explicit before installation.
• A demand-response rule that throttles or pauses units when reservoirs are low, so cooling yields to supply during genuine shortages rather than competing with it.