Energy: don't stop now

John Rothchild carried his calibrated bucket to his neighbor's house. He measured the shower's hot-water flow. Then he pulled one of his handy ''10-cent solutions'' from his pocket - a plastic shower flow controller. He showed that it cut the flow by more than half without weakening the spray too much.

This small tale of a latter-day Johnny Appleseed, planting energy savings instead of trees, has a larger meaning. It ranges from oil shortage to oil plenty, from energy waste to energy thrift. It proves that Tocqueville for once was wrong about Americans - and it calls on them to keep it that way.

For Tocqueville said that Americans almost always are reluctant to do anything inconvenient even when convinced the end is worth it. And taking steps toward energy efficiency looked mightily inconvenient to people accustomed to thinking of the cost of energy last in virtually any undertaking. But so many American individuals and institutions took these steps anyway that projections of future energy supply have been dramatically improved. Indeed, many Americans ingeniously minimized the inconvenience and instead found freshly satisfying life styles through wasting less and enjoying it more.

The challenge now is to keep up the momentum toward conservation and renewable energy in the face of oil ''glut'' and price cuts. This is where John Rothchild comes in again. He calculated that his neighbor's family of four could save $90 a year on hot water with that little shower flow controller.

Ninety dollars here, ninety dollars there.In a book called ''Stop Burning Your Money,'' Mr. Rothchild leads us point by point through the energy savings from insulating, plugging leaks, replacing equipment, using solar water heating. He developed the Department of Energy's ''no cost/low cost'' approach to household conservation. Now he is spreading the word, describing pitfalls, telling how to audit the energy auditors. He sees conservation moves not as pullbacks but as investments, and he estimates the annual return (from 2 percent to 7500 percent) on each.

Here is a most encouraging reminder of what individuals can do if they have not done it already. It is going to get increasingly more expensive not to act, as Harvard energy expert Daniel Yergin points out in the book's preface. Many large companies have realized this and achieved remarkable results. People in their homes can follow suit.

But it is not only a matter of action. On one energy ''investment'' Mr. Rothchild notes that the pitfall is: ''Investor must have conserving attitude.'' For all Americans to have this attitude would really send a new Tocqueville back to the word processor.