A water crisis, too?

Must Americans face a water crisis like the oil crisis before they stop wasting water? In some areas there is already sufficient sense of crisis so that market-pricing of the once virtually free resource is being urged to spur conservation, efficiency, and distribution. It is argued, for example, that subsidized water rates steer farmers to wasteful forms of irrigation rather than ones using dramatically less water but costing enough more to be uneconomical now. Since farm irrigation accounts for almost 80 percent of US water consumption, it is obviously of central importance to develop policies for its utmost efficiency.

But the drive toward such policies at the local, state, and federal levels requires an awakening of what might be called a national water conscience: a realization that this seemingly abundant resource has to be treated like a scarce one if future crisis is to be avoided.

Americans with their flowing faucets might think from time to time of the African woman spending hours of her day fetching water. They might even think of their own Californian countrymen during the drought of several years ago. With water rationing imposed upon them, they devised all sorts of ways to cut back. They found that much of their previous usage was sheer waste. When the rationing was lifted, they offered the country a valuable example of changed attitudes. As a Sausalito woman said, ''I will never again waste water.''

It is changing attitudes and then acting on the change that has been such a challenge to Americans in various matters over the years. The need to save water, like the need to save oil, calls for dusting off the observation of Alexis de Tocqueville about Americans in the past century:

''Whenever they are required to undergo a privation or any inconvenience, even to attain an end sanctioned by their own rational conviction, they almost always refuse at first to comply.''

There have been enough temporary water scares here and there so that Americans should have a rational conviction of the importance of saving water even at some inconvenience. (The Californians during the drought were reported to have achieved their savings without substantial change of life style.) The time is here for actually complying.

One of those little shower control devices can save 60 gallons of water a day for a family of four taking daily showers. If they take hot showers, 30 of the gallons would be hot, saving energy along with water.

Then, too, the used household water - the so-called ''gray'' water - could be recycled for lawn and gardening purposes, with some care depending on detergent content.

Inconvenience, maybe. Privation, no. One estimate: homes and businesses could cut water use by a quarter with little or no discomfort.

Why now, when some parts of the country have had more rain than usual, and water does not exactly dominate the news media?

Because threatening trends are underway.

There is extensive ''mining'' of America's vast underground sources of water, which total at least 33 trillion gallons, comparable to 200 years of discharge from the Mississippi. Not all of this water is accessible for environmental and economic reasons. Mining it means taking it out from the ''aquifer'' storehouses faster than these are naturally recharged. The undesirable effects can include the subsidence and cracking of land, salt water intrusion, declines in spring and stream flow. Indeed, irreversible environmental damage can be done by destroying the aquifer to the degree that it can never completely recharge again.

At the same time, whatever the quantity of water available, the quantity of usable water is threatened by acid rain, industrial discharge, agricultural chemicals, and other impurities. An environmental conference in Stockholm has just warned the US about acid rain. The Senate is in the process of trying to fashion controls on it. Meanwhile, last month, the US's first national statistical assessment of rural water conditions reported that close to 29 percent of rural homes had sufficient bacteria in their water to constitute a potential health hazard.

As with energy, the conservation of water is a prime means of ''production.'' Americans have been conserving oil partly out of ''rational conviction,'' in Tocqueville's phrase, but also under the lash of high decontrolled prices. Must water prices move up in the same way to impel the nation's water conscience? Must Americans be disabused of the vague feeling that water is a right, with government policies based on need and entitlement rather than what the market will bear?

In California the Rand Corporation has suggested a way to shed some light on the matter. It proposes that the state continue to ''wholesale'' water to local water districts. But then these districts could freely buy and sell water among themselves, with prices going up or down as in the marketplace.

It seems a contradiction in terms - trading water like any other commodity. Yet, whatever the policies chosen, the awareness of water as the valuable resource it is must be established - and acted upon by all.