Let’s look at what it takes to harvest rainwater and the estimated cost. For a more detailed discussion download the full sustainable living guide.
The amount of water you can harvest is determined by three factors:
The size of your roof catchment area
The amount of rainfall that your suburb gets in a year
The size of your storage tanks
As a rough guide, we estimate that 1 mm of rain on 1 m² of roof = 1 litre of water
What do you need to build a rainwater harvesting system?
For a basic rainwater harvesting system, you will need the elements below:
You need a water tank. Normally the size of the tank depends on the amount of space you have at home. Estimate R2 500 - R2 850 for a 1 000 L tank.
This tank needs to stand on a solid base and be supported. The tank is generally placed underneath or close to the downpipe. Estimate concrete plinth: R600 for materials (assumed DIY labour) and plumbing fittings and piping R400 – R1 000.
An initial pre-filtration is required to keep the leaves and bigger particles out of the tank. Estimate R1 000.
Now that the water can be collected in your tank, you need a small pump to pressurise the water so that you can use it. The size pump will depend on the amount of water you need. Estimate booster pumps: R1 675 (0.37 kW) to R10 249 (variable speed drives and pressure control).
If you do some of the work yourself and can get away with a basic system, it can cost as little as R6Â 000.
Figure 1 shows the components of a standard rainwater harvesting system.
What can I use rainwater for?
Generally, harvested water is used as grey water to flush toilets, wash hands or for other non-potable (drinking) purposes.
In the next six of our 13-part series, we look at savvy plans to put in place to minimise load shedding from disrupting your family’s life.
Ready to invest in a power or water saving solution for your home? If you’re an SA Home Loans client, we'll help you finance it through your home loan.Â
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