How Rainwater Harvesting Transformed Our Urban Home, Part 2
As I mentioned in Part 1 of this series on rainwater harvesting, we treat overflow from our rainwater tanks as a resource instead of something to be shunted off-site. Every harvesting element on our property feeds into another element on the property where excess “waste” can be put into productive use. These feature include tire ponds and swale trails.
The tire pond is a small pond built from a tire and some pond liner. Water flows from our primary southern roof to the pond; overflows afterwards into the first of our garden “swale” trails. The tire pond and created wetland provides habitat in our garden where diverse flowers bloom and small creatures congregate. We often forget that even small critters like insects need a drink!
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Urban Swale Trails
Urban swale trails are an innovation that happened here in Calgary. They are basically features that adapt drainage infrastructure (Big O pipes) and turn it into water harvesting infrastructure. Basically, we dig a level ditch where we want the water to infiltrate, lay down a big O pipe at the bottom, and then cover it completely with mulch. One or both ends of the pipe are then connected to an overflow or a roof. That’s it.
As the water enters the swale trail, the wood mulch absorbs the water and starts to decompose. Wood can hold an incredible amount of water, which is where the drought-proofing nature of our garden comes from. Worms also find their way into the paths and shuttle nutrients between the swales and the garden beds. After 2-5 years, you can either add more mulch to the path to refresh it or excavate the material for the most amazing compost you have ever seen. Because it’s mulch, it’s also quite light and easy to manage.
A couple of things to consider if you are planning to do this. Don’t have water infiltrate too close to your home’s foundation; I recommend staying at least 10 feet back. I also recommend holding water in a rain tank and then connecting the rain tank overflow to these swale trails when needed; it gives you a bit more control and things won’t get overwhelmed during a really wet season.
Here’s a three-part video series we did on constructing urban swales:
Water Design and the Garden
As a result of getting the water right, the garden pretty much grows on its own once it’s established. The mulch stores the water and holds the mycelium network, which forms symbiotic relationships with most plants (with the exceptions of brassicas like broccoli, kale, cauliflower, etc.) Our garden needs very little additional water on years with average rainfall.
Here are some general principles that we follow for growing gardens that require little water and weeding:
- Plant densely: We try and plant very densely. One of the best resources on planting like this is Square Foot Gardening. It’s a great guide and you can usually find his book around because it’s so popular.
- Companion planting: Plants are not loners. They like to be close to their buddies, just like us. We interplant all of our crops together—it confuses the pests, looks beautiful, and provides more production in our tiny space. Carrots Love Tomatoes is a great book for learning how to companion plant.
- No bare soil: We use mulch and dense planting to keep the soil covered at all time. The only thing we break this rule is in the spring. We’ve found that it’s good to let the top crust of the soil dry out a bit to reduce slug pressure.
- Stack in space: We utilize vertical space with plants that like to climb: Squash, beans, and sunchokes, to name a few.
- Stack in time: Different crops produce at different times so we plan the garden so that we’re always receiving yields. We also have a solar passive greenhouse and a small microgreens setup in our house.
We love good food and at this point, can’t imagine not having a garden. Even the food at the local organic market pales in comparison to what comes out of our small space. Eating food from your backyard when it’s just ripe—there’s nothing better!
Then there’s the bonus of having a garden is that our kids innately understand where food comes from and how our property should be designed to support us, not the other way around. That’s the best benefit of all.
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