Claire 🐝 Cardwell en Design & Sustainability Network, Sustainable Design, Architects and Technicians Owner • Blue Designs Architectural Designers 28/11/2016 · 2 min de lectura · 1,3K

What you need to know before installing a rainwater harvest system

 What you need to know before installing a rainwater harvest system

Water is vital to life and is such a precious natural resource that it makes sense to collect every drop of rain and re-cycle grey water and back-washed pool water. In fact you can reduce your water bill by as much as 90% by harvesting rain water & grey water.

Rainwater harvesting is the collection, filtering and storage of rainwater for reuse on site. It's usually collected from roof tops and can be used in the garden, for car washing and for drinking water with proper treatment. Collection of rainwater can help mitigate flooding of low lying areas and reduces demand on wells which may enable ground water levels to be restored. In addition rainwater harvesting in urban areas reduces the need for clean water in water distribution systems and less generated storm water in sewerage systems as well as a reduction in storm water runoff polluting rivers and lakes.

Rainwater harvesting is not new - around the 3rd century BC farming communities in Balochistan (now located in Pakistan, Afghanistan and Iran) used rainwater harvesting for irrigating crops. Not many people know that Venice depended on rainwater harvesting for centuries as the lagoon that surrounds Venice is brackish and so not suitable for drinking.

It is not complicated to install a rainwater harvest system - here are some tips :-

• The tank should be placed on a solid flat, level surface.

• Your house must have gutters and accessible down-pipes.

• Several down-pipes can be directed to one tank.

• A leaf catcher or first flush filter should be installed on each down-pipe. 

• Generally a pump will be needed to pump the water from the tank into the garden, so you’ll need accessible electricity.

The rainwater tank doesn't have to be placed next to your house, they can go anywhere in your garden or be buried underground so long as the top of the tank is below the level of the filter or leaf catcher.

Rainwater tanks are quite large - a standard 5000l tank is about 2.2m high and 1.8m in diameter. The biggest down fall of rainwater harvesting systems is a lack of storage capacity, so it's best to buy the biggest tank that space and budget allow. The simplest way to calculate what size tank you will need is by taking a look at the size of your roof. Generally 50 to 100m² roof = 750L to 2,200L tank, and 200 to 400m² roof = 2,500L to 10,000L tank.

We are all becoming increasingly aware of the importance of water to our survival as well as the decline in water quality and reliability of supply. Water conservation needs to be a way of life. If we all try and save water we can make a huge difference to the environment.

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About Claire Cardwell

What you need to know before installing a rainwater harvest systemI think it's vital to talk about all aspects of Architecture - whether it be planning, construction, design or green building. I have written 3 E-Books & over 110 articles. Please feel free to let me know if you have any queries regarding architecture, planning & construction & I will assist you.

I am originally from the UK  and moved to South Africa  in 1999. I started Blue Designs in 2004 after working as a Driver for Avalon Construction on a luxury home in the Featherbrook Estate. In my spare time I am a keen artist and photographer.

I can be reached on +27 11 025 4458 (mobile landline) or at

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Claire 🐝 Cardwell Dec 1, 2016 · #13

#11 Unfortunately the water infrastructure has not been maintained or planned very well here either @Kirsten Horner - as the city gets more and more overpopulated and dense we are about to see some major problems with water supply, this has of course been exacerbated by the drought....

Claire 🐝 Cardwell Nov 30, 2016 · #12

Thanks for the share Mohammad!

Kirsten Horner Nov 29, 2016 · #11

Thanks Claire. We live with water saving and water restrictions here in Queensland, Australia - in between the floods! The larger water management infrastructure is under pressure and hasn't been planned or managed well for future supply, so everyone has to do their part on their own property.

+1 +1
Claire 🐝 Cardwell Nov 29, 2016 · #10

Thanks for the share Elizabeth - we can all live for a while without electricity, but now the water cuts here in Joburg are a reality - you simply can't take clean drinking water for granted anymore.

+1 +1
Elizabeth Bailey Nov 29, 2016 · #9

Something all property owners should think about.

+3 +3
Claire 🐝 Cardwell Nov 29, 2016 · #7

#4 Thanks Rod, you are certainly right about being a lot more aware of water usage when you rely on stored water.

Claire 🐝 Cardwell Nov 29, 2016 · #6

#5 Thanks @David B. Grinberg! I am certainly a lot more careful with water these days..... Part of the problem here in Joburg is a badly maintained old infrastructure, apparently about 40% of all our potable water is wasted through leaks....