What is the largest single use of water in our homes? The American Water Works Association points to our toilets with an average of 26.7 percent of total household usage for a single family home. With every flush we bathe our feces, immerse our urine, and send it all away with 1.6 gallons of water, the current code requirement for all toilets. This 1.6 represents a 75 percent reduction of flush water from past years, but it still empties the earth's reservoir of pristine water much too quickly.

Sarah's eighty-three-year-old father, Carl, has considered his water usage a lot recently, especially his flushing habits. He wants his grandchildren to have plenty of clean water, so he's decided to do what he can to conserve. Much to his wife's consternation, Carl places buckets and dishpans along the drip line of their roof. When it rains, his containers collect, and Carl then funnels the water into old milk jugs, hauls it into the house, and pours it into the toilet tank after every flick of the handle. He's even reprimanded his wife for flushing when he wasn't around to fill the tank. This practice keeps Carl fit (water is heavy after all) and conserves the precious, rock-filtered groundwater buried deep in the earth.

Americans drain almost 47 billion gallons of water a day for domestic use. According to the U.S. Department of the Interior's 2000 Geological Survey, 85 percent of the population gets their water from surface sources, while the remaining 15 percent draws from underground aquifers. How much of this 47 billion gallons a day is flushed? Roughly a fourth or 11.75 billion gallons. It's hard enough to say that number let alone comprehend it, but try imagining a lake of pure water 10-feet deep, 3 miles long and almost 2 miles wide-that's our daily flush. Think of a lake 365 times that large for the amount we flush in a year.

Like Carl, Sarah and I get our water from the cavernous earth, 365 feet down. We thought our flushing habit seemed innocuous, part of a circle. After all, the water we drew from the well returned to the ground through our septic system, so what's the problem? Then we read and discovered that yes, that water returns to the aquifer, but only after many long years of trickling through the earth. Recent carbon dating of water in North Carolina found that the deepest waters were over 35,000 years old. The circle we imagined with our septic system is far more ancient and fragile than we could ever comprehend.

The same can be said for the 85 percent of the population dependent on rivers and reservoirs for drinking water: yes, they are part of a circle (that water cycle learned about in elementary school), but also, that circle is fragile and in many ways, beyond our control.

We just do our business and watch the clean water, now contaminated with our own waste, disappear. Where's it go? Far away, we hope, to some treatment plant that takes care of such matters. But this human-constructed system is far from efficient, riding the wave of thousand-year-old clean water into oblivion. The recent severe droughts have awakened the whole country to the precarious nature of this water supply and our foolish usage habits. If global climate change continues and droughts persist, car washes and lawn irrigation might become felonies, and flushing the toilet, a misdemeanor.

What's to be done? Don't flush, for starters, especially after every tinkle. Install low-flow shower heads or even composting toilets. Wash only full loads of laundry or dishes in super efficient appliances, or maybe do the dishes by hand. Definitely fix any plumbing leaks which account for almost 14 percent of the daily household use. And consider Carl's trick of gathering rainwater for other uses.

We've got our pails lined up along the drip line, and we've also utilized a new low-tech, water-saving device in the shower-a handy five-gallon bucket. You know all that cold water that runs through the pipes while you wait for the hot? Well, that now collects in our bucket. And then, that too gets poured into the toilet, saving a little of this precious mystery we're so dependent on, yet know so little about-clean, pure water.