We have been looking at adding a rainwater tank or barrel to our newly build workshop in the yard. The plan is to use the water that we harvest off the shed to water our raised vegetable garden beds.
Unfortunately there is a possibility, albeit small, of the water we harvest not being clean enough for our vegetables. There are many reasons why this could be a possibility, you can read about some of them, with the corresponding studies, here.
Some of the possible contaminants that could find their way from your roof to your rainwater system are:
- Bird Droppings
- Rotting Leaves
- Dust
- Salts
- Pollens
- Insects
- Bacteria
There are a few simple ways that we can make the water is 100% safe to use for our vegetable garden:
- Install a First Flush Water Diverter and Leaf Filter
This allows the first few litres of water that comes off the roof to drain, instead of going in the rainwater tank or barrel. The first few litres of water will contain the vast majority of the muck and contaminants from the roof, and by filtering it out, you won’t have to deal with the contaminants making it into the garden. - Water the ground, not the leaves
By watering the ground, and not the leaves of your plants, you avoid contaminating your leafy vegetables as any contaminants that get past the diverter and filter will be naturally filtered by the soil and roots. This is generally good practice anyway, as it is a more efficient way to water your garden, but it also has benefits for contaminants. - Use Chlorine Bleach in The Tank
Once a month you can add a tablespoon (15 ml / 1/2 oz) per 100 litres to your reservoir. This should help to kill anything in the water, but be of low enough quantity to affect the plants. After you add the bleach you will need to wait 24-hours before using it so that the bleach can dissipate. (source)
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A good video showing the installation of a First Flush Downpipe Diverter in South Africa can be found here:
Another good review and video from someone else here in Australia can be read about here, and the video watched below:
So, by following these three steps we should be setting ourselves up very well for using our captured rainwater to water our vegetable garden beds.