Design, DIY, Gardening, Green Building, Water Management

Storing Rain Water WITHOUT a Tank

I’ve got water on my mind lately. The H2O on our planet doesn’t get nearly the attention it deserves, and because of this we’ve polluted or made unusable a sizable chunk of what little fresh water we have on this earth. So here we have a growing population, a dwindling source of drinkable water, increasing climactic variability that’s wreaking havoc on the reliability of rainy days, and at the same time we’re ripping down forests and natural areas that hold and store water in favor of concrete slabs and suburbs.

Okay, personal anxieties and future Mad Max scenarios aside, I figure I should get ahead of the game and pursue some knowledge (and hopefully an eventual career) in water management, as its importance is only going to grow in my lifetime.

Typically not a lot of thought is put in to where our water comes from. What pops in your head when you think water storage? I’m guessing for most of us (including myself) our minds fill with mountain lakes and rivers, and structures like water towers and reservoirs. But these visible water features are just the tip of the ice cube in your glass. In fact, the majority of water is stored beneath us – not just in underground caverns as one might imagine, but mostly it’s soaked like a giant sponge in the soil and dirt.

Rich, organic soil can hold several times its weight in water. 

In fact, Rob Avis of Verge Permaculture discusses his rainwater tanks that hold roughly 5,000 litres of water, but the healthy soil and plants in his garden can hold that amount and more! Plus, the water in the soil is more useful: it’s underground (doesn’t evaporate quickly), it’s cleaned my microbes and it’s highly accessible by the thirsty plants that need it.

Nature is a lot better at storing water than our crazy human contraptions

As a modern, device-building human, we’re preconditioned: if we’re asked to catch rain water, immediately our thoughts go to 1. we’ll need a giant funnel, which 2. goes in to a giant bucket.  And voila, we have rainwater harvesting:

Our typical mental image of catching and storing water.

But what about a more resilient, cheaper system? Ben Haggard of Santa Fe Permaculture says: “The cheapest way to store water is in the soil”

To put it in perspective, healthy soil can hold roughly 1/3 of it’s weight in water. Therefore if you have a 1 foot deep bed of soil in your yard, that’s equivalent to a 4 inch deep pond across your entire yard! Likely that holds just as much if not more water than what that complex rooftop system you want to build can handle.

So in summary, an effective means of storing rainwater includes:

  1. A deep layer of rich, organic soil
  2. Contouring the landscape to catch and direct water
  3. Get some drought-tolerant plants
  4. Plant densely to shade the soil
  5. Mulch your yard and garden beds heavily (mulch can be compost, woodchips, straw etc.)

And that’s it! And it will make for a healthy, productive and low-maintenance yard. Compare this to a standard grass lawn with a thin layer of unhealthy, compacted soil, which requires constant watering and fertilizers.

The Queen Mary Permaculture Garden – staying green through the dry months

The proof is in the pudding: at the permaculture garden where I’m volunteering here in Vancouver, this dry spring has brought wilty, brown plants and lawns everywhere…but not at this garden that has used these techniques!

There are swales that catch the rain on its way down the hill, plenty of leaves and straw for mulch and thick, tall plants that shade the soil from the many hot sunny days. We’ve barely watered the garden and it’s happy and green.

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