Fashion has always been a bellwether. In this millennium, designers have been responding to ecological anxieties by trying to create a collective voice of conscience within the industry. For all the public enthusiasm for “fast fashion,” brands at the high end and their creative directors are taking a longer view.

These efforts have included embracing sustainability in manufacturing and in the building of new boutiques. Designers have been proactive in finding fabrics and dyeing treatments that are biodegradable or do not harm rivers and land. Fashion people have also lent support to campaigns to save endangered rain forests and other ecological causes.

Tuesday is World Water Day, an initiative instigated by the United Nationsfollowing a summit in Rio de Janeiro in 1992. And the designer Giorgio Armanihas committed to raising awareness about improving access to safe drinking water, working with Green Cross International and supporting, for the second year, the Unicef Tap Project in the United States.

“Water is such a simple word — but like all simple words it has a profound significance,” said Mr. Armani, whose show in Milan last month was preceded by a screen projection of waves and news of his Acqua di Giò fragrance.

The objective of World Water Day 2011 is to focus international attention on the impact on urban water systems of rapid urban population growth, industrialization, and uncertainties caused by climate change, conflicts and natural disasters.

“I have always been very sensitive to environmental issues, especially those concerning water, an element that I love very much — regenerating, precious and essential to life,” Mr. Armani said. “For this reason, last year I joined the Tap Project.”

Throughout his career, the maestro of Milan has used water and its blue-green colors as a visual symbol — not least in his last Privé collection, when the liquid surfaces of high-tech fabrics gave the effect of watery reflections. The names of his best-selling fragrances riff on acqua, the Italian word for water.