Thoughts at water level

In the end, they say, what matters is how one deals with pressure. With due respect to those who thrive on high-pressure living, I disagree. What matters is strength. That much I've learned from plumbing.

Not, I hasten to add, that I am anything but an amateur in this damp and grimy sport of pipefitting. But I have gone far enough to know its agonies and exhilarations, the despair of a pinhole leak and the delight of well-tightened threads. I have stood helplessly at midnight in a rainfall of my own making, with no parts at hand on a holiday weekend, and have cursed my unwillingness either to let well enough alone or to call in a professional.

But I have also hummed smug and happy tunes when, after hours of work among copper and hot solder, I have opened the main valve, heard the water go ''pssht!'' into the system, and found nary a droplet on the outside of my new-made, strong joints. I concede that, in a world that praises only the more visible crafts, plumbing is an art largely overlooked. Yet if satisfaction can be measured by one's ability to channel unruliness toward fruitful ends, plumbing is surely satisfying.

I came upon plumbing rather by necessity. I was a teen-ager when our family built, on a remote island in a Canadian lake, a summer cottage. We founded it on a ledge high above the water; we framed it with peeled balsam poles; we sided it with shiplap pine boards from a mill forty miles away; and we roofed its steep pitch with green tarpaper. And when it was done, we set about digging a well. But the rocky soil was so unyielding, and the lake so pure, that we gave it up. Why not, we reasoned, build our own water tower for lake water instead?

So it was that, after mulling over plans during the winter, we came to install a full-blown water system. And such a system it was! To the visitor, perhaps, it was nothing but a few ordinary faucets, with here and there a glimpse of black plastic pipe beneath the floor-joists. But to us it was a triumph. Down by the shore was the pump and its engine. Behind the house was a cedar pole structure on which perched two fifty-five-gallon steel drums. And below the drums, overlooked by all but connoisseurs of the craft, was our pride and joy: an assemblage of cast-iron elbows, couplings, nipples, valves, and unions which, through progressive reductions in pipe size, brought together the water from the two huge, threaded barrel bungs into a single half-inch plastic pipe.

We spent hours designing that single bit of piping - sitting cross-legged on the floor in the back room of a hardware store in North Bay, surrounded by bins of fittings and the advice of clerks. And slowly, carefully, we puzzled out a kind of iron octopus which had no more joints than it needed, but enough to allow us to put it together. For that was our great fear: that, forty miles and a boat ride from those bins, we would find we had miscalculated, and that the only way to put that last piece together would be to have one person hold a wrench to the pipe while the others picked up the entire house and screwed it onto the thread.

In the end, of course, the house stayed on its footings and the pipes came together. And in the years since, the idea of that system has persisted. To be sure, the tank is now an aluminum one, the pump runs on electricity from a generator, and parallel pipes beneath the floor reveal, to a practiced eye, the presence of hot as well as cold water. But the goal has remained the same: to so master the rules of pressure that one gets the world's most thoroughly common yet altogether precious commodity - water - just where you want it to be, and nowhere else.

I thought of these things the other day when we drove along the base of a dam at a man-made suburban reservoir. Behind its grassed and placid slope, I knew, tons of water rose high above our heads - enough to spring leaks in a thousand thousand basements. I realized it had been there for years. Yet the sight made me a bit uneasy. What tremendous pressure, I thought, exerted against so delicate a piece of earth. What if it gave way?

And with that I remembered the rocky cliffs on the shores of those Canadian lakes - deep, straight slabs thrusting up from the lake floor. Their wrinkled granite rose calmly above the surface, finally to curve back and disappear under the roots of the giant white pines. Against that rock rode a weight of water far greater than the dam held. To think of those cliffs, however, was not to worry about pressure at all. The idea that the water could somehow push apart and gush through those rocks never crossed the mind. One thought instead of strength - the unyielding solidity of that granite.

Many times since, when the pressure of events has seemed to build, I've thought of that example. If it has a lesson, it is a lesson of language: that the word ''pressure'' comes to mind only when one fears a lack of strength. In the presence of an irrevocable, rocklike stability, the notion of pressure seems peculiarly irrelevant.

Which is why, as I say, what matters is not that one learns to deal with pressure. What matters, for the practiced eye, is to recognize strength.