Marg Evans
Rain Barrels and Rain Gardens
May 30, 2008
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Marg EvansRain Barrels and Rain GardensMay 30, 2008
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Why consider a rain barrel or rain garden? Once set up, both systems are low maintenance and contribute to your community's sustainable water management and clean air! There are advantages both at home and within the community to using soft, pure "living water". One centimetre of rain falling on an 1100 square foot roof area will produce about 1,145 litres of water. With four gutter outflows on each roof, one rain barrel at each corner can collect approximately 258 L from one centimetre of rain.
At home, warm, oxygen-filled rainwater straight from the rain barrel to the garden provides plants with water neutral in ph, free of salts, minerals and chlorine. Rain water is more efficient than treated or "hard" well water at dissolving the nutrients in the soil and passing those on to the plants. If collected properly, rainwater will be free of natural and man-made pollutants and contribute in replenishing our aquifer and groundwater supply; versus adding to our storm drain run off, which picks up contaminants off the roads. Within our community, there are lawn-sprinkling restrictions in effect throughout the summer, yet you can water your lawn/garden with soft rainwater any evening you want from your rain barrel, and know you are not paying for the pumping and treatment of this water. Even in rainy regions, over 70% of rainfall occurs in fall and winter, not in the summer, when we use 50% more water on our lawn and gardens. In the end, we reduce our taxes, as it reduces municipal and regional water-related costs.
Rain barrels: you can choose to buy a ready-made one, convert an oak barrel, or try a do-it-yourself model made from recycled trash cans. They need some basic appendages - the barrel, a lid with screen/mesh to keep out mosquitoes, an overflow spout, and a hose connector. It helps if it is slightly elevated, either on blocks or a stand, unless all your watering is downhill from your barrel.
If you are in the city, your overflow could lead to the storm drain, or, if you wish, add another barrel for storage to allow you a good supply. Plants flourish not only on the quality of the rainwater, but also on the considerably warmer temperature over water coming from underground.
Rain gardens are natural filters, and absorb rainwater running off roofs, driveways and sidewalks. When nitrogen-rich leaves and lawn clippings are washed into storm drains, they reduce oxygen and ultimately lead to the suffocation of fish and other aquatic species. Unfiltered water that reaches our waterways after running across roads, parking lots and driveways enter our streams and lakes, contributing to up to 70% of harmful pollutants contained in these waters. A rain garden captures this run-off and the soil acts as a super filter, first slowing down the water and then purifying it, mimicking a miniature wetland!
What do you need to create your rain garden? First, pick your location on a downhill slope where rain naturally pools and snowmelt gathers in spring. You may choose to access rainwater from your roof by running a drainpipe or rock/gravel path from the house to your planned garden area. You could choose to design this as a landscape feature portraying a dry creek bed. Next, determine what type of soil you have… is it sandy (drains well), loam, or clay-like (holds the moisture)?. Dig the garden area 8 inches deep in the middle for sandy soil areas, and up to 20 inches deep if your soil tends more towards water retaining-clay. Mix your soil with compost (25%), topsoil (25%) and sand (50%). The sides of your garden slope gradually upward, giving you areas of varying degrees of moisture for plants. Native plants are ideal for rain gardens as they do not require fertilizer and tolerate our climate and soil types well. Native plants also handle a wide range of temperature and tend to be drought-tolerant as well.
By choosing local native wetland edge vegetation such as wildflowers, rushes, shrubs, sedges and small trees, you also support biodiversity and wildlife within your garden. A great reference book for our area for these plants is Plants of Southern Interior British Columbia edited by Ray Coupé, Roberta Parish and Dennis Lloyd. Once you have chosen your plants, be careful to plan out their locations, placing those more tolerant to high moisture in the deepest area of the garden. Once the plants are in, it is time to add mulch to your garden. Mulch helps regulate soil temperatures and retain moisture, while providing organic matter and humus to the soil as it breaks down. You can choose organic mulch (grass clippings, bark, evergreen needles, sawdust/shavings or leaves) or inorganic (rocks or gravel). You need generally 3 - 4 inches of mulch on top of your soil, leaving a small circle bare around each plant to prevent excess moisture rotting tender roots or slugs and rodents making their homes here. Water the plants if it does not rain, at least twice a week for a month or so to allow them to establish a deep healthy root system.
As your new garden grows and thrives, enjoy the birds and butterflies it attracts. While you are doing so, realize the environmental benefits not only improve our water sustainability, the trees and shrubs you plant improve our air quality by removing smoke, dust and other pollutants from the air. Air temperatures in summer are also lowered by shading concrete and buildings, and by plants that return humidity to the air through their natural evaporative cooling system. For more information on rain gardens visit: How to Build a Rain Garden and Wikipedia's entry on Rain Gardens. For more on the Cariboo Chilcotin Conservation Society's Water Wise program, go to Water Wise or call 250 398-7929.
- Marg Evans, Coordinator, Cariboo Chilcotin Conservation Society
Cariboo Chilcotin Conservation Society
Unit 201, 197 2nd Ave North Williams Lake, B.C., V2G 1Z5
Phone/Fax: 250 398-7929 • ccentre@ccconserv.org • Coordinator: Marg Evans
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