What is rainwater harvesting and how does it work?

Is your water bill putting a pinch on your wallet or do you want a more sustainable home?

Many of us rely on the water that comes from our taps to be safe for drinking and cooking. But this clean water is also used for washing clothes, bathing and watering the lawn – all activities where you can easily replace or supplement municipal water with a rainwater utilisation system. Once installed, these systems make rainwater available for your daily needs, which helps you save on municipal water use and costs. 

How does rainwater harvesting work?

While the idea of using rainwater to complete household tasks can sound strange at first, you may be interested to know that rainwater collection is a practice that dates back for millennia! There’s evidence it was used in both ancient Greece and ancient Rome.

When it rains, the rainwater that is not absorbed in soil will fall into street drains, eventually finding its way to streams and rivers. Rainwater harvesting is a way for you to collect and store some of this extra water to reuse in your home routine, instead.

The best part? Rainwater is a completely free source of water that gives you a higher degree of control over your water supply.

According to the UN and the World Health Organization (WHO), the average person needs between 50-100 litres of water per day to meet most basic needs.

So how much rainwater can you collect? Various sources estimate that each square metre (m²) of roof space collects around 1 litre (L) of water for every millimetre (mm) of rainfall.

To estimate the maximum amount of water you can harvest at home, you can use the calculation: 

• [roof size in m²] x [monthly rainfall in mm] x [1 L]

For example, if we look at the monthly rainfall pattern for your geographical area and find it’s an average of 100 mm per month, we can calculate that a 100 m² roof can capture around 10,000 litres of rainwater each month. 

If a water-conscious family of four uses 400 litres of water per day, the 10,000 litres of water collected can provide most of the 12,400 litres they’d need in a 31-day month! Even if you don’t aim to fully replace municipal water use, this amount is more than enough to supplement for water-intensive activities like flushing toilets or using the laundry machine.

Understanding rainwater collection 

At this point, “rainwater collection” might conjure the simple image of a barrel left outside to gather rainwater. And it’s true: The most basic method of collecting water involves positioning a bucket or barrel underneath the downspout of your home’s roof, to direct the water that’s falling.

But not all methods are created equal – it all depends what you want to use the rainwater for and how much you want to collect. 

While the barrel method can help you collect enough rainwater to water plants or wash your car, it’s a comparatively small amount, and certainly won’t make up for all your family’s monthly water needs.

On the other hand, more sophisticated rainwater harvesting systems require water filtration, storage tanks, and booster pumps to bring the clean water back into your house. Not only does this give you the much larger storage capacity you need to reuse rainwater for household activities that don’t need clean drinking water, it can also store a 2-3-month reserve of water recommended by our experts.

To start with, booster pump systems ensure you can rely on comfortable water access in your home, every day.

Learn how a booster solution makes consistent water pressure the new standard.