A drippy faucet is a waste of water, but when thousands of gallons roll off the roof and into the storm drain, the waste is monumental by comparison. Especially when it's so easy to capture the water for reuse.

The process can be as simple as setting out a standard plastic garbage can and using a bucket to retrieve the water. A second option is purchasing ready made 250-gallon (or larger) systems with pre-assembled inlet and outlet fittings.

A third, less expensive choice is making your own rain barrel system. How much water you can capture is a function of the size of your roof and the size of your system.

Every 1,000 square feet of rooftop sheds about 600 gallons of water for every inch of rain. In an average year, Sonoma County receives 40 inches of rain, enough to generate 24,000 gallons of rainwater for every 1,000 square feet of roof area.

Assuming it's going to rain again, your roof will yield more rain water than even the largest storage container can hold. A friend in Sonoma purchased a 2,500-gallon tank last year, for example, which was filled to overflowing by the very first rainstorm.

Your three primary planning considerations should be: how much water you anticipate catching; how much space you have available for the tanks; and how much you can spend.

If your water storage requirements are limited, here's a simple process for making an inexpensive rain catchment barrel. If you need extra incentive, the City of Santa Rosa is offering a materials rebate of $0.25 per gallon of storage.

Materials Required:

; Recycled 20- to 55-gallon food-grade barrel with a removable lid (try Friedman's or other hardware stores)

; 3/4-inch copper hose-bib faucet

; 8 inches window screen (1/16-inch mesh)

; Silicon sealer

; 2-inch male PVC threaded adapter

; 2-inch electric conduit nut

; Two 2-inch PVC street elbows

; 2-inch PVC pipe (length will vary)

; PVC glue

Tools Required:

; Cordless or electric drill

; 1-inch paddle bit

; 2-3/8-inch hole saw

; Jigsaw

; Adjustable wrench

Inlet: Using a jigsaw, cut a 6-inch inlet hole in the barrel lid. Cut screen into an 8-inch circle. Apply silicon sealant to top of lid, around perimeter of hole, and apply screen.

Overflow Drain: Drill an outlet hole about 2 inches down from the barrel top using the 2-3/8-inch hole saw. Apply silicon sealant on inside and outside perimeter of hole and insert the threaded adapter into the barrel, taking care not to get sealant on the threads. Tighten the conduit nut on barrel's inside using wrench.

Glue overflow street elbow to the male adapter using PVC glue. Cut a piece of 2-inch PVC pipe that will extend downward, leaving it about 2 inches short of the ground. Glue to overflow street elbow. Then glue the other end to another street elbow, pointing in the direction you want the water to flow (away from the house).

Then cut another section of PVC pipe long enough to carry overflow water to a drainage swale, garden or storm drain. Glue screen material to end of pipe.

Garden Hose Spigot: Drill 1-inch hole about 4 inches from bottom of barrel using paddle bit. Apply silicon sealant around perimeter and thread 3/4-inch hose bib through hole. Tighten with wrench.

Measure height of barrel and cut rain gutter downspout accordingly. If needed, purchase a 90-degree downspout adapter to reach inlet hole.

Leave a gap between end of downspout and top of barrel for easy removal of leaves and roof debris.

My quest for catchment systems took me to Urban Farmer, Farm Supply, Friedman's, Loomis Tanks, hardware stores, lumber yards, even Home Depot. The odyssey's home run was Guerneville-based Jesse Froehlich, owner of BlueBarrel Rainwater Catchment.

She supplies complete, DIY barrel systems that come with all the fittings. The brilliance of her business model is sourcing high-quality food grade barrels she can sell for a fraction of the cost of a new barrel.

Typical barrels, including related supplies, average $2-$5 a gallon. BlueBarrel systems cost $0.60-$1.28 a gallon. Froehlich also holds regular workshops that teach essential assembly techniques — before you go home and start your own adventure.

BlueBarrel systems are connected by pipes on the bottom of each barrel. Froehlich says they have created systems with as few as two barrels and as many as 42, although there literally is no upper limit.

To contrast, all other barrel systems have interconnecting drainage tubes and spigots that are located on the sides of the barrels, leaving as much as 15 gallons of standing water in the bottom of each one.

Most people locate their barrels along the side of the house, often along the garage wall. Choose a shady area, keeping the water cool enough to prevent bacterial growth.

Choose a dark-colored opaque barrel, like Froehlich's signature blue barrels, to inhibit the sunlight infiltration that leads to algae growth. If your rain barrel is white, cover it with dark colored paint.

If you want to learn more about DIY water catchment systems, Froehlich will present a rainwater harvesting talk at the Sonoma-Marin Fair in Petaluma from 3:30-5 p.m. Saturday and will give a hands-on installation workshop from 10 a.m.-4 p.m. Aug. 2 in Petaluma.

For more information, email Jesse Froehlich at info@BlueBarrelSystems.com or call 394-5009.

For a list of other local suppliers and installers of rainwater harvesting equipment, visit ci.santa-rosa.ca.us and search for "rainwater harvesting."

(Tom Wilmer has been a licensed general contractor since 1986. Email him with your questions at tomwilmer@aol.com.)