As Michael and I were scheming together on the design of the new bike shelter, we saw the potential for it to do more than just protect our wheels from the elements. Being adjacent to our recently installed mini-forest garden, the new structure was a perfectly placed to act as a passive catchment surface.
With that idea in mind, we designed the corrugated metal roof of the shelter to slope gently towards the east, where falling precipitation drains into a gutter. From there, it travels into a perforated tube (scavenged from a defunct French drain) that Michael hung with wire to coil around the canopy of the crabapple tree. In a large rain event, water flowing into the coil falls through the perforations and onto the garden in a beautiful sheet pattern.
The results have been stunning. Within weeks, the plants that benefited most from our passive watering system shot up in growth and looked more vital than before. We’re excited about seeing how the system holds up, and improving on the design in other contexts.
- Reduces dependence on energy-intensive and chlorinated tap water
- Increases utility of water flows arriving on site
- System was constructed from scavenged and upcycled materials
- Looks pretty darn cool, especially in the rain
Observations for improvement:
- The coil works well only in a heavy rain – and even then, the water only makes its way about halfway around the tree. This could be altered by adjusting the number and size of holes, as well as the slopes of the catchment surface and coil.
- The weight of the coil puts a small amount of stress on the branches of the crabapple tree. An older tree would handle the weight just fine.
- Some of the species, such as bunching onion and strawberry, still require some hand-watering. More drought-tolerant species would be ideal
- The fact that rainwater is directed to the surface, rather than the root zone, means that a good deal is lost to evaporation (although this is mitigated by the straw mulch)