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Rainwater tank: underground or overground?

Posted by Barry Nutley on 29 June 2009 at 9:26 am

In rainwater harvesting retrofit projects, the cost of installing a kit underground can seriously impact the financial viability, and ultimately put people off the idea. Below are some considerations to help you make the right decision:

1) Pros for underground:

a). No unsightly equipment in the garden, especially if you are installing a tank bigger than, say 300 litres or so.
b). It's suitable for a small garden or where the space is otherwise restricted.                                                                                                              c). Less risk of "brackishness" (this is discoloration due to bacterial action at 12 degrees C and above) in summer due to warming of the leaf debris at the bottom of the tank. This problem could be reduced by thinking about location (a shaded north facing area, perhaps), and considering some form of natural shading (such as a plant).
d) Negligible risk of frost damage to tank, piping and pumps in winter. This may not be a problem depending on where you live.

2) Pros for above ground:

a). Easy to install and lower installation costs.
b). Easier to maintain in case of change of scenario or pump failure.
c). Suitable for commercial and other installations where the visual and aesthetic criteria are less important. Of course it is possible to provide a suitable, natural "cover".

In summary, there is realistically only one rule. For a full domestic system, then bury it underground (unless you want your "whites" to go brown). But, if you don't mind a bit of discolouration in your toilet, with a suitably sized/positioned system, it is feasible to have an above ground system providing a "semi" domestic system. So don't necessarily dismiss the idea if you don't want to dig up your garden.

Happy harvesting.

Photo by Mooganic

About the author: Barry Nutley is co-founder and director of Viridis Energie Consultants

About the author: Barry Nutley is co-founder and director of Viridis Energie Consultants

If you have a question about anything in the above blog, please ask it in the comments section below.

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