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Monday, 9 September 2013

A Better Rainwater Harvesting Solution

I first heard about this solution about 10 years ago while trying to find a better solution to deal with the fact that we funnel all our rainwater off site one day, and then irrigate our gardens using municipal water the next day.
Arum lilies make great plants for rainwater gardens
If we are really forward thinking, we use green solutions such as water tanks, in which we try to catch as much water from our roofs as possible, store it, and then pump it out into our gardens. This really is a great solution. But I'd like to suggest an even better option.

Our soils were created to be natural water tanks. Depending on their composition, they (like sponges) have the ability to catch and hold water. They catch hundreds of thousands of litres of water, releasing it slowly over a period of time, either upward to the roots of plants, sideways into rivers, or downward into the groundwater below. Good soil is essentially a reservoir for plants to survive through periods of dryness. So why do we funnel it off into tanks, or even worse let it drain away into the stormwater system?

Normal rainwater could be funnelled into the soil where it belongs, and excess water overflows into the stormwater system.
The answer to this problem is actually an age old one, and it lies in using plants, and in shaping the soil to slow down and catch the water.

Instead of using the downpipes to carry water straight into our stormwater system or at least into tanks, the water would flow from the roof down the drainpipes and into a catchment area with plants that would naturally be found in wetlands. These plants can tolerate both waterlogged and dry conditions depending on the season. The water can then drain away naturally into the soil.

Vancouver's innovative stormwater solution
Another application is alongside large paved areas, like parking lots, driveways and roads. The water that comes off these areas usually has a mixture of oils, litter, and other pollutants that end up in our rivers and eventually the sea, creating huge long term problems. We should be creating filtration areas before the water runs into any kind of stormwater system.

This can be a beautiful way of bordering or softening hard areas like parking lots and roads, and in a water thirsty country like ours is an ideal way of conserving water in the place where it should be conserved.


Diana Studer said...

rain gardening, yes absolutely!

Gardening Dreamz said...

Hello Ross, I think this is a great idea but the only problem with this is you can’t control the amount of water flowing into your garden bed at any one time. Thus, tanks are the best solution for re distributing rainwater into your garden because you can control the amount of water being released so your plants are given the correct amount to remain healthy. This would be implemented through an irrigation setup from yours controlled via a node (controller) as I am sure you’re aware. Certain plants would not be happy sitting in too much water as this will encourage a fungal attack on the roots and kill your plants eventually. Obviously we know what happens when they don’t have enough water. So supplying them through an irrigation system is the best method, but using recycled water as much as possible. Only in very dry conditions where it hasn't rained for a long time and those tanks are empty I would resort to town water. This however is something that should be avoided if you want have a sustainable garden. I totally agree with your ideas of recycling water but I think you need to have more control over its distribution so more care can be applied when using it.

Thanks Chris knowles

stoneware70 said...

Hey Chris, thanks for your thoughtful comment!

Yes, tanks definitely have their place, and can help reduce your dependance on municipal water in a big way. I see this form of rainwater harvesting as a compliment to other forms of water conservation.

This option makes use of normal rainwater that flows off hard surfaces like parking, driveways and roads. Any excess water that doesn't drain into the soil, flows back out into the hard surface area, and can then preferably be channeled into tanks or if necessary, the storm-water system.

Louisette said...

Interesting idea irrigation by stormwater , wonderfull place.

Unknown said...

This is a great idea. I am always looking for ways that I can go green. I would love to be able to reuse my rainwater. I didn't know about creating filtration areas on the sides of paved areas. I think that this should start being a standard so that we can do more to conserve water.
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