Creating a rainwater collection system for your garden is both environmentally responsible and budget friendly. Using natural rainwater reduces the amount of chemically-treated city water going into your garden and it is free to collect. Plants thrive because rainwater is naturally soft, and collection barrels protect areas under downspouts from erosion due to heavy runoff. Follow the simple guidelines below to harvest your own rainwater.
Use the roof of your home or garage for an ideal collection area. It is already collecting water every time it rains, and the gutter system funnels the runoff to a specific location under each downspout. The average 25 foot by 40 foot home roof sheds approximately 600 gallons of water during one hour of moderate rainfall. If you have two downspouts, you can collect up to 300 gallons under each one. The more barrels you have, the more water you can collect.
Identify the location of your downspouts. The gutters and downspouts on your roof are already designed to divert and funnel water and debris off the roof. They are made from aluminum or plastic and either material is appropriate for rainwater collection. Install garden debris filters at the top of each downspout to avoid debris collecting in the barrels. Clean the filters periodically so they do not become clogged. Use a fine-mesh, aluminum window screen to cover the opening of each rain barrel. This allows water in but keeps most insects out. If you live in an area prone to mosquitos, you may also want to invest in a tight-fitting lid, as mosquitos often breed in standing water.
Place barrels under chosen downspouts, preferably close to the garden. 55-gallon drums are most common. Choose barrels with a spigot near the bottom for easiest water transportation. The spigot should have an on/off valve. You will want to raise the barrels off the ground using cinder blocks. This increases water pressure and makes it easier to fit a watering can under the spigot. Dig out a four-inch deep area under the cinder blocks and fill the area with ¼-inch pea gravel. This allows you to level out the cinder blocks and keep the barrels steady. The gravel also diverts water away from your foundation in the event of a heavy rain that causes barrels to overflow.
If you begin to notice algae build-up or an odor in your barrels, invest in a refillable dispenser containing bacteria and enzymes that are used to clean ponds. They come in sachets that sit in the barrel and keep the water clean, and they are available at most garden supply stores.