Rain as a Resource: How to Build a Rain Barrel

Editor's note: It is legal to harvest rainwater from roofs in San Juan Capistrano as long as the water is kept in a container that keeps mosquitos out.

After weeks of sunny weather, we're reminded that it's still winter in Southern California. There's rain in the forecast for this weekend, which means it's still worth your while to build a rainwater harvesting cistern, or rain barrel. Harvesting rainwater reduces storm water runoff, putting less stress on our public water infrastructure. It also provides high-quality irrigation water for your garden, lowering your water bill.

Devote an hour or two of your time in the next few days to build this rain barrel and you'll be ready to "harvest" this weekend. Here's what you'll need:

• one 55-gallon food-grade barrel (These are available at feed stores or online.)
• one bulkhead set (Ask for it at your local aquarium supply.)
• one brass garden faucet (Available at your local hardware store.)
• one piece of mesh or window screen
• one PVC elbow fitting, optional (Available at your local hardware store.)
• silicone adhesive for sealing

Directions:

1. Purchase a clean, 55-gallon food-grade plastic barrel. Do not reuse a used barrel or one you retrieved from the dump.
2. Cut a hole the size of your downspout into the top of the barrel or lid. A hole or saber saw will do the trick.
3. Using the silicone adhesive, affix a piece of mesh or window screen over the hole in the lid to prevent debris or critters from falling in. If you need it, you can attach a 45-degree elbow to the end of your downspout to reach your barrel.
4. Unscrew the bulkhead and place the threaded stem against the outside barrel about 4 to 6 inches above the ground.
5. Trace around the stem and cut out the traced hole.
6. Place one of the rubber gaskets on the stem and push it through the hole so that the base stem and rubber gasket are still on the inside of the barrel. The stem should fit snugly.
7. Slide the second gasket onto the stem that is now protruding out from the barrel. Next, screw the washer onto the stem.
8. Tighten it down against the gasket, but avoid overtightening. You can now thread the brass garden faucet into the bulkhead and affix a hose.
9. Apply silicone adhesive to the areas around the bulkhead that you think water might still leak from.
10. Position the barrel under your downspout and do a rain dance!

NOTE: The bulkhead thread size will determine what size faucet can be inserted. Faucets have thread sizes that can be made larger or small with adapter pieces found in hardware stores.

How much rain can you catch? According to the rainwater harvesting rule of thumb, you can collect 600 gallons of water per inch of rain falling on a 1,000-square foot catchment area. In this case, the catchment area would be your roof, and your rain gutters would siphon that volume into your barrel. Again, you're using a 55-gallon barrel here, so you'll fill up on a light or moderate rainfall event.

Is your roof bigger than 1,000 square feet? Use this simple calculation to find out your maximum roof runoff in gallons.

Take the square footage of your roof and multiply by feet of rain expected for the event (convert from inches by dividing by 12), then multiply by 7.48 gallons per feet cubed to figure out your harvest potential.