Oceanography

In 1960, industry and agriculture in the United States each used about one hundred and fifty billion gallons of water a day. Industrial needs are large and varied. It takes, for example, a hundred thousand gallons of water to manufacture an automobile; an average Sunday paper consumes about two hundred and eighty gallons of water in its processing; a ton of steel requires sixty-five thousand gallons of water in the making. The location and size of water supplies determine to a large extent the profit or loss in a business operation. A twenty-two unit apartment house may require more than three thousand gallons of water daily; a laundromat with ten washers may require more than 1,800 gallons of water a day; a car wash that can handle twenty-four cars an hour will need nearly 8,000 gallons of water daily; a large paper mill can easily use more water than a city of fifty thousand people.

Clearly these businesses are not inexpensive to operate in locations with poor water supplies. This water may cost as much as twenty-three cents a thousand gallons from the municipal supply. To operate a laundromat successfully, it may cost an additional three to seven cents per thousand gallons to have “soft” water. Special processing for many industrial water uses adds to the cost.

Not only does the world food supply depend upon water, economic development occurs where there is sufficient water to support, first, the population, and later, the industrial demands. One has to know only a little history to know that civilization flourished with adequate water supplies, and that industrialization has occurred in areas of abundant water for power and for transport of goods. Populations have been forced to move with changing water supplies. Archaeologists have traced the growth and decline of Indian villages in the southwestern United States as water declined in abundance or purity. It has been man’s ability to transport enough water from areas of abundant supply to less favored areas and to otherwise supplement local supplies that has permitted the development of arid and semiarid regions for agriculture and industry. The technologic demands for further such development will certainly become greater in the next few decades as land with marginal water supplies is pressed into use.

There is much value in the idea that land should be reserved for the use to which it is best suited. Covering good agricultural land with parking lots and highways and tearing down orchards to build more houses takes out of production land with high agricultural yields and eventually forces cultivation of land that does not have adequate water for growing crops, requiring the installation of expensive irrigation systems.

The same dependence on water plagues industry. As water demands increase and supply becomes scarcer, or more polluted and more expensive, industry moves toward abundant and inexpensive water supplies. Industrial water generally must be of at least as high quality as drinking water; in some instances even more restrictive specifications must be met. Some industries buy water from public supplies, and then treat it further to meet individual needs. The amount of salt in water used in ultra high pressure steam power plants can be only 1 ppm, while the manufacture of rayon requires water with no more than 100 ppm total dissolved solids. Whiskey can be distilled with water containing 1,000 ppm total solids, so that distilleries may remain longer in polluted areas than steam power plants! Water for cooling, used in numerous industrial processes and accounting for a high percentage of industrial water use, must be non-corrosive and contain extremely low percentages of minerals. Another important factor is temperature; it is obviously important to avoid expensive pre-cooling before water can be used. Some industrial uses for distilled or demineralized water are in leather-finishing processes; the tanning processes sometimes require water with low bacterial content. Each industry has its own special needs for various types of water.

It was once possible to produce power with a wooden paddle wheel and natural stream flow. The water was fresh and clean, and even if it did become polluted the effect on the operation of the mill was small. Today it takes millions of gallons of high quality water to operate boiler-powered electrical plants, and millions of gallons of stream water to produce hydroelectric power. Electricity production accounts for sixty percent of industrial water use.

Why other industries require so much water is often a bit obscure. The uses for water in food canning will serve as an illustration. Water of drinking quality is used to clean raw foods, which are then transported to various operations in the factory by belts, flumes, and pumping systems (accounting for a major portion of water used). After peeling, fruits and vegetables are rinsed thoroughly in water-especially important if the peeling has been done chemically. Green vegetables are put into hot water or steam to inactivate enzymes and to wilt leafy vegetables to facilitate packing. Very high quality water, free of chlorine, is used for packing, or is used in packing syrups and brines. Containers are sterilized and cooled, both steps using large quantities of water. And finally, water may be used to transport waste materials from the factory.

As another example, the textile industry uses vast quantities of water for washing raw materials, in dyeing and bleaching, and for washing the finished product.

When we survey water use today, we find that industry and agriculture use 96 percent of the total consumed, and that only about 4 percent goes for direct personal uses. One important fact emerges-we tend to think of drinking water as being purer than that for irrigation and industry, whereas the facts are that the tolerance range of humans is greater than that of some plants or of the canning industry. Moreover, as technology becomes more complex, the necessity of treating natural waters for specific uses also grows more involved and costly. As our knowledge of botany, of zoology, of all other aspects of living increases, we find that more and more controls on water composition are desirable.

Study of the water requirements of many species of plants shows that some thrive on high sodium waters; others wilt. With a rapidly expanding world population, it becomes more and more important to reap the maximum production from each acre of fertile land. We find that plants must be fed a diet of water whose composition is tailored to the individual crop.

We are beginning to realize that the natural drinking water supply, even without problems of pollution, or naturally introduced organisms, is not necessarily always the best. Many natural supplies have enough fluoride to cause bone and tooth damage; others have enough salt to be damaging to sufferers from high blood pressure, even though they are satisfactory for normal healthy persons. At the same time that we are discovering the significance of the many elements occurring naturally in water, we are adding new substances faster than their effects can be assessed.

Whatever the solution to the ethical and political problems of control of water composition, some predictions can be made. “Pure” water, water like that we must drink but with even less dissolved material, will be required for most industrial and agricultural uses. With increasing utilization of stream and underground water we find that the great reservoir-the oceans-will be needed more and more. If we are to use the oceans they must be at least as un-salty as streams. This gives us a clear target for the future.

What are the requirements today and of the future for this kind of water? In 1960 the United States used three hundred billion gallons a day; in 1980 it is estimated that withdrawal of water will reach six hundred billion gallons a day, and that by 2000 it will be nearly nine hundred billion gallons daily. Water use grows faster than population. The estimates indicate that when population is doubled, water use will triple.

If we can hope that by the year 2000 the rest of the world will have reached a level of affluence more nearly equal to ours, we must think of water requirements based on per capita numbers. If we use nine hundred billion gallons a day for three hundred million people, we will be operating at a rate of a little over three thousand gallons per day per person. The best estimate of world population at that time is about seven billion people. If so, the amount of fresh water required will be close to twenty thousand billion gallons a day, an amount about equal to the entire world stream flow.

True, a world in thirty years with uniform international affluence is not very realistic, but even if the growth of affluence is slow, the growth of population is not, so a fresh water demand of this magnitude is certainly foreseeable under any circumstances. The question arises-is that much fresh water available? If not, what can be done about it?