In these economically stressful times, free water is a good thing. So gathering rainwater from rooftops into barrels for use on the landscape makes sense, even if you don't consider yourself an environmentalist.

The Pennsylvania Resources Council and Nine Mile Run Watershed Association are both offering information and education on this ecologically friendly method of conserving water. Nancy Martin-Silber, an environmental educator who coordinates the council's Rain Barrel program, notes that they call their classes watershed awareness/rain barrel workshops.

"We define what a watershed is so people can conceptualize it."

The easy definition of a watershed is an area of land that drains into the same body of water. Watersheds are separated from one another by increased elevation, hills, a ridgeline or mountains. Sometimes they are referred to as a basin.

"We talk about human impact on the watershed," she says. "How does our behavior affect the quality of the watershed in our rivers and streams. Everything from car care, to pet care, lawn and garden care, the products we purchase, use and dispose of can affect the watershed,"

Using a rain barrel is one easy way to significantly cut the amount of waste water that ends up in waterways or sewer systems. One 1,000 square-foot house can harvest about 24,000 gallons of rainwater annually that can be used to water lawns, shrubs and gardens. Ms. Martin-Silber cautions that some older types of roofing materials can contaminate the water, so it should not be used to water vegetable gardens. But it's fine for lawns and ornamental plantings.

The resources council classes (see schedule at end of story) show participants how to retrofit a 55-gallon food-grade barrel for water collection. Hardware is supplied in the class; barrels are not. Ms. Martin-Silber suggests two barrels for most homes. The council will have demonstrations on rain barrels and composting as part of the second annual Pittsburgh Design Fair for House and Garden on Sept. 28 at The Priory on the North Side.

The Nine Mile Run Watershed Association, meanwhile, promotes rainwater collection by installing rain barrels at homes within the watershed, which encompasses Edgewood, Swissvale, Wilkinsburg and part of Pittsburgh (ZIP codes 15208, 15217, 15218 and 15221). The 133-gallon barrels, which are custom-made in Lawrence County, were designed by the association with Carnegie Mellon University to meet the needs of the average homeowner (see related story above).

Its Web site, www.ninemilerun.org, explains the project and how to get a barrel installed. The cost ranges from $100 for residents of the watershed to $200 for those outside the watershed. Information: 412-371-8779, ext. 17.

The Pennsylvania Resources Council will sponsor rainwater workshops at:

• Noon today at Urban Gardener, North Side.

• 7:30 p.m., Sept. 23 at Boyd Community Center, Fox Chapel.

• 10 a.m., Oct. 4 at Natrona Heights Environmental Center, Harrison Hills Park.

• 7 p.m. Oct. 28 at Whole Foods Market, East Liberty.

The cost is $30 per person/$40 per couple and includes hardware to outfit a rain barrel. Information: 412-431-4449, ext. 247 or www.prc.org. Design Fair tickets are $5 in advance, $7 at the door, available online at www.pittsburghdesignfair.