Industry and water

Industry accounts for roughly 20% of global freshwater withdrawal, and the figure conceals processes with completely different profiles. Some industries use enormous volumes at low quality and return almost all of it; others use modest volumes at extraordinary quality and consume much of it.

What industry uses water for

Cooling

By far the largest volume across industry as a whole. Quality requirements are low; the constraint is availability and discharge temperature.

Process water

Water that participates in the process — dissolving, reacting, washing. Quality requirements vary enormously.

Cleaning

Dominant in food and beverage, where hygiene regimes require frequent cleaning-in-place at drinking quality.

Product incorporation

Water that leaves as part of the product. Small in volume, entirely consumptive.

Ultrapure water

Water so free of dissolved and particulate matter that it is aggressive. Required in semiconductors and pharmaceuticals.

Semiconductors: purity beyond drinking water

Chip fabrication rinses wafers with ultrapure water at 18.2 MΩ·cm resistivity — the theoretical maximum for water, set by its own self-ionisation. Producing it requires reverse osmosis, deionisation, ultraviolet oxidation and degassing in series, and the pretreatment rejects a substantial concentrate stream.

A large modern fab may withdraw on the order of 10 million litres a day. Leading fabs recycle a large majority of process water, so consumption is well below withdrawal — but the facilities are large, individually visible, and increasingly sited in regions where that visibility matters.

Textiles: a quality problem, not a quantity one

Dyeing and finishing use large volumes and return most of them — but the returned water carries dyes, salts, and process chemicals. The sector is concentrated in countries where effluent regulation is often weakly enforced, and its water impact is dominated by what is discharged rather than by what is withdrawn.

The larger share of the textile sector’s total water footprint is upstream, in cotton cultivation — which is agricultural water use, and which drove the diversion that destroyed the Aral Sea.

The trend

Industrial water use per unit output has fallen substantially in high-income countries over recent decades, largely through recirculation rather than through process change. A pulp mill today may use a tenth of the water per tonne that its 1960s equivalent did, having closed its water loops rather than reinvented papermaking. That is the general pattern: the gains come from using the same water repeatedly.