NEW BOOK Water. By Steven Solomon.

TO WRITE a history of water was a good idea. Since life depends on water, it has been man's constant companion from the moment his forebears emerged from the sea and, you could say, even before. Human affairs have therefore been intricately related to water. But man has mistreated his friend, and now, it is said, the world faces a water crisis. There is too much of it in some places, too little in others. It has been acidified, dirtied and squandered. It should no longer be taken for granted.

The first three-quarters of Steven Solomon's book is an account of the ascendancy and decline of various civilisations, seen through a watery lens. The survey starts in antiquity with Egypt, Mesopotamia and the areas round the Indus and the Yellow River. It runs through the Roman empire, the building of China's Grand Canal in the seventh century and the Islamic era that followed. Then come the stirrings of mechanical development in medieval Europe that preceded the invention of the steam engine in Britain, the arrival of the industrial age and the mass production, and consumption, of the American century. Along the way the reader learns about aqueducts, dams, canals, waterwheels and devices for lifting water, as well as sanitary inventions, naval battles and maritime voyages of discovery. The thesis is that enduring civilisations are underpinned by effective water control.

As a contention, this may seem banal, yet the tour d'horizon might also have been a tour de force. One difficulty, though, is that Mr Solomon so often strains to make water more important than it actually was. The Roman empire, it seems, fell apart because it lacked the "unifying impetus" of an inland waterway like China's. It was hydroelectric power, ie, water, that powered the aircraft factories and aluminium smelters that in turn played a "decisive role" in America's victory in the second world war. Sewers and piped water gave the West "comparative economic and politically legitimising advantages over its cold-war rivals". The distance-shrinking Panama Canal was another triumph for water. And it was water, or rather its absence, that obliged eighth-century Islam to go out and trade and conquer. Indeed, the Muslims' use of camels-a proxy for the precious liquid-in crossing deserts just showed the importance of water. No surprise then to learn that the defining geographical condition of America's Far West was not its Far Westernness but, yes, water scarcity.

Matching the over-claiming is the overwriting. Clashes are existential, audacity is breathtaking. Almost every change is a revolution, every expansion an explosion. Catalysts abound. Indeed, water, it is said at the outset, has an "extraordinary capacityŠto catalyse essential chemical reactions", making it the Earth's "most potent agent of change". In truth, water is hardly ever a catalyst in ordinary conditions.

In other respects, the problem is under-, not over-performance. The 97.5% of water that is salty, for example, is hardly considered, except as a means of transport. This leaves quite a hole in a history of water. And though much is made of the steam engine, ice scarcely merits a mention.
In the last quarter of the book, Mr Solomon abandons history and turns to the water shortages of today and the political clashes they may cause. Competition for Nile water is acute between Egypt and Ethiopia. Fierce disputes also divide Turkey and its southern neighbours in the Jordan basin. With India and China, both prodigious consumers of ever-scarcer fresh water, the rivalries are mostly, though not entirely, internal. And in many places, notably the United States, north Africa and the Middle East, aquifers whose water may have lain undisturbed for 10,000 to 75,000 years are now being recklessly drained, with no prospect of a refill for an aeon or two. Everywhere it is the poor who suffer most.