FORT WORTH, Texas — The water slowly drips off of the eaves of the house in the silvery-gray light of a storm just passed. Glancing out the window, it would be easy to assume that the roof had shed little more than the few fat drops I see falling.

But I'd be wrong.

An estimated 1,240 gallons of water can pour off my 2,000-square-foot home during a 1-inch rainfall.

Go ahead. Get out your calculator. The Texas Water Development Board estimates 0.62 gallons of rainwater per square foot pours off roofs for every inch of rain that falls.

The drip, drip, drip I see out the window adds up. I would have realized it sooner if it formed a huge pool in my yard. But rainwater streams through the downspout, the driveway and into the storm sewer. Or it gushes into the yard, where at least it is filtered through soil to help remove impurities.

Either way, I don't see the pond of water that has fallen. I only see the drops.

That's true of so many environmental consequences. We don't see the silent and invisible stream that gathers behind us and all that we own.

My project in recent weeks has been to rectify that, at least as far as my roof is concerned. I bought a rain barrel.

I was lured into the world of rain barrels after several nearby residents raved about them. The rainwater the barrels provide is far better for plants, these folks said. It's untreated water that otherwise would run off the property. Why not capture it?

I was a bit skeptical. Rain barrels collect water that runs into gutters and downspouts. The only gutters on my home are short ones that prevent water from dropping in sheets over my doorways.

Would it work?

Gardener's Supply, www.gardeners.com, and Smith & Hawken, www.smithandhawken.com, are two sources for rain barrels ranging from $130 to $250 for 40 to 65 gallon barrels, or go to www.organicgardeningtx.com and click "Products and Services" for $175 oak barrels. Otherwise, if you are handy, you can convert a less expensive barrel to collect water and release it with a spigot.

The first night the rain barrel was delivered, I put it outside without hooking it up. I set it under the eaves. It rained lightly, as if on cue. Even without being hooked up, the rain barrel collected about 20 gallons of water, which eventually was used to water vegetable beds.

I connected the barrel to my downspout that collects water from a 3-foot gutter. The second week of April, it rained about an inch during a noisy nighttime storm. The following morning, I had 55 gallons of water in my rain barrel.

That's from just one rain storm.

I got out my calculator. If it rains 35 inches a year, an oft-cited average for North Central Texas, that is 1,925 gallons of water that I can collect and use on house and garden plants. It will replace 1,925 gallons of water that otherwise would have come out the end of a hose or a sprinkler.

And it is collected by only a 3-foot-long gutter.