Can harvested rainwater be used for drinking purposes? Yes! And here’s how

According to the Department of Water and Sanitation, less than 1 percent of South Africa’s 14 million households use harvested rainwater as their primary supply for domestic use. The reason for this massive underutilisation of a relatively simple and cost effective water source is that our water has traditionally been cheap. But droughts, the virtually unprecedented water crises in the Western and Eastern Capes, and the imminent water scarcity we’ll face in the coming years mean that water tariffs are set to rise – dramatically.

Can harvested rainwater be used as potable water (drinking water)?

The answer is a resounding yes, but you’ll have to filter and purify (disinfect) it first. Fortunately, Builders has you covered with our top-notch DIY water purifiers.

Legal considerations

Please note, however, that South Africa’s water related and health acts don’t provide a comprehensive legal framework for deriving potable water from roof harvested rainwater. To make sure you’re in the clear, check with your local municipality and find out what by-laws they have in place.

Why does harvested rainwater need to be purified?

Rainwater itself is of a very high quality, but, when it rains, it gets contaminated by pollution in the atmosphere. Once it falls onto a roof, it picks up dust and chemicals in addition to various other pathogens like E.coli from bird and rat droppings. Items like a leaf-eater, first flush diverter, and filter screen all help filter out unwanted matter before the rainwater even reaches your storage tank – but more needs to be done before it’s 100% safe to drink.

UV Steriliser Filter System

The UV sterilisation method is one of the best water purification processes available today. In a nutshell, there are two phases involved.

  • In the first stage, the water is run through two filters, each of which performs a cleaning function. The first filter (the 5 micron filter) removes large solids from the water. The next filter (the carbon filter) removes organic matter, 99.9% of any chlorine residue (if you’re filtering your mains supply), and addresses issues of water clarity (turbidity).
  • In the second stage, the now clear water is run through a chamber lit by a UV light. The UV light penetrates the cell walls of pathogens and disrupts their DNA activity. This inhibits their ability to reproduce, which in turn renders them harmless.

Once the water supply (either from your storage tank, your mains supply, or a mixture of the two) has been filtered and disinfected, it’s safe for human consumption.

The GoPure 5-Stage Water Purifier

  • Ultra-filtration works by passing pressurised water through a series of filters and a membrane, each of which removes targeted impurities. Please note that this particular filter is designed to receive water from your mains supply only (which is certainly something to consider for health reasons).
  • As described in the above video, the spun polypropylene filter removes suspended particles. The granular carbon and block carbon filters remove organic matter, chlorine, any odours and increase water clarity. Ultra-filtration membranes have extremely fine pore sizes (0.002-0.1 microns), which remove microscopic bacteria and other potentially harmful pathogens. Lastly, to ensure that the water is as healthy as possible, the mineral ball filter adds beneficial minerals to the water.

To learn more about the many benefits of rainwater harvesting, its purification for drinking and cooking purposes, or the purification of your municipal supply, visit your nearest Builders and spark up an informative conversation with our friendly staff. Alternatively, browse and shop online here.

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