One of my father's pet peeves when I was growing up was wasting water. It used to madden him when my mother would rinse the dishes before putting them in the dishwasher or leave the tap running while wiping down the countertops. Unfortunately, in those gender-determined times, he didn't have much say, so we all did things my mother's way -- with great liberality.

As an adult, I've been free to take a more conservative approach, but have never managed to live up to my father's high standards -- until this summer when we began a renovation of our loft. For the last several weeks, our only source of running water has been the tub. We can't even get to it directly. From the living room, where we're doing all our cooking with a microwave and toaster oven, we have to go out into the hall of the apartment building and through another doorway to get back into our space. It's kind of like going to the river in olden times. We make the trek out with our pitchers, fill them up, and then make the much heavier trek back home.

In order to reduce the number of trips, as well as the time spent bent over the tub, we've adjusted our methods. We use things (glasses, clothes) more often between washings than formerly, discard unused water in plants, wash produce with a wet cloth, scrape dirty dishes instead of rinsing them and soak dirty things in a soapy bucket rather than wash them under an open tap.

In our current situation, these water-saving measures are easier than the alternative. But it also turns out that they're just plain easy. There's no reason we couldn't do them under ordinary circumstances and one major reason we should -- water scarcity.

Contrary to common perception, water is a limited, if renewable, resource. Less than 3 percent of the earth's supply is fresh, and two-thirds of that is locked up in glaciers and polar caps, leaving us only 1 percent to use. Seeding clouds doesn't increase the amount (though it can make more fall as precipitation in a particular area). Desalination can, but it's expensive, and is only an option in coastal areas or places with brackish water.

However, the supply of freshwater isn't as much a problem as our profligate way with it -- the fact that we flush away so much without even bothering to use it first. As the human population continues to expand worldwide and at home, the strain on resources will only grow, particularly in water-starved areas like the American Southwest.

In the past, the solution was always more dams or wells, but neither is an answer when freshwater supplies are already tapped out. Anyway, dams, as we now know, can devastate entire ecosystems. So, for that matter, can excessive water withdrawals from rivers. That's what happened to the once lush Colorado River delta, which is now a mud-baked plain. Depleting groundwater reserves can have the same effect, since rivers, lakes and wetlands depend on them as water sources. Moreover, the lowered water table can deprive plants of needed access to underground water.

We humans already use more of the planet's available freshwater than our share. According to United Nations estimates, our take is currently 54 percent and will rise to 90 percent in 25 years, if current trends continue. That would leave only 10 percent for all other living things.

What to do? We need to start using water more efficiently. Since agriculture is the single largest user (and waster) of water, most of the savings need to happen there. But there's plenty of room for improvement on the home front, too. Take a look at the suggestions below and you're sure to find one or two you can easily act on. Remember, water savings are not an all-or-nothing proposition -- every little bit really does help.

—Sheryl Eisenberg

Filling up at the tub. Water is heavy -- a gallon weighs 8.33 pounds. If we all had to fetch our water personally, you can bet we'd use a lot less.

Water wasters. The toilet is the single largest water user in the house. The clothes washer is second. However, drips and leaks can trump both.

ONLINE RESOURCES NATIONAL GEOGRAPHIC UN Highlights World Water Crisis SCIENTIFIC AMERICAN Tapped Out PBS Thirst NRDC'S ONEARTH Turning Oceans into Tap Water US GEOLOGICAL SURVEY Ground-Water Depletion Across the Nation CALIFORNIA URBAN WATER CONSERVATION COUNCIL H2ouse

The Colorado River Delta. In this satellite image, the river is the dark blue patch at the top left. It once flowed into the Gulf of California at the lower right of the picture, but no longer. To see the stunning full-sized photo, and get a detailed description of the landscape, go to NASA's Visible Earth site.

Scarcity around the world. Over a billion people lack access to clean drinking water, and two and a half billion lack adequate sanitation services.

...and in the U.S. Though we are blessed with a comparatively large freshwater supply, water scarcity is a problem here, too. The seven states through which the Colorado River flows are in constant conflict over their allocations from the river. And in the Southern Great Plains, the Ogallala aquifer, the largest in the U.S., is seriously depleted. Less land can be irrigated as a result, and drinking water quality in some parts is threatened.