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Rooftop Rainwater Harvesting

Why waste the clean water that falls on your roof, just to rely on purchased utility water? Rooftop rainwater harvesting is a simple and effective way to reduce or eliminate your dependence on utility water, therefore saving you money and building your self-sufficiency and resilience.  It is as simple as collecting and storing rainwater from your roof for later use. Using a guttering system, the goal is to capture and divert rainwater from your rooftop to a tank, for either potable or non-potable use. It may be pumped, or if the tank is elevated, gravity fed into your house to replace utility water. It can also be used for irrigation, landscaping, and other non-potable applications. Rooftop rainwater harvesting is a cost-effective solution to water scarcity. It is a sensible strategy for managing water at your home and for many households should be considered a priority.

We have a great tool for calculating how much rainwater you can harvest from your rooftop. Take a look at our Rooftop Rainwater Harvesting Calculator.

How Does Rooftop Rainwater Harvesting Work?

Rooftop rainwater harvesting systems typically consist of a catchment area, such as a roof, gutters, downpipes, water storage (tank), in some cases a pump, and the plumbing required to connect to your house or garden
water demand. They can be complex or very simple depending on your needs and resources. The catchment area collects rainwater and diverts it to the storage tank, where it is stored until needed. The stored water can then be used for a variety of non-potable applications, such as watering plants, washing cars, and flushing toilets. If your local government regulations allow it, the water may be connected to your potable water plumbing. Where both rainwater and utility water are used, there are simple methods available to maximise your use of rainwater and minimise your draw on the utility supply. For example, clever valving arrangements or storage tank top up systems.


What are the Benefits of Rooftop Rainwater Harvesting?


In addition to our favourite benefits of water efficiency – to save money, increase self-sufficiency, and build resilience, rooftop rainwater harvesting can offer several additional benefits:

  • Tank storages can act as attenuation devices, therefore reduced stormwater runoff and erosion.
  • Similarly, the more storages such as rainwater tanks are in a catchment, the greater the reduction in peak flows occur during significant rain events. Therefore, leading to reduced flooding.
  • Clever irrigation systems can be designed to use stored water to delay the application of water and therefore improve soil moisture and plant growth.

What Should You Consider When Designing a Rooftop Rainwater Harvesting System?

Before installing a rooftop rainwater harvesting system, there are several considerations to keep in mind:

  • It is essential to consider your roof size and slope. This will determine the amount of rainwater that can be collected and the size of the storage tank that is required. Our calculator will help you do this!
  • The amount of water needed for your application should be considered when sizing the storage tank. In many cases you will want to maximise the opportunity and collect the greatest amount of rainwater possible, using the calculator mentioned above. However, if you are simply wanting to supply a low demand use, you may wish to minimise the storage size for that use.
  • Depending on your location, the condition and material of your roof, and the local air quality, you may need to test the rainwater to ensure it is safe for its intended use. This is particularly the case if you intend on drinking it!
  • Some areas may have regulations or permits required for rainwater harvesting systems. This should be investigated for your area before proceeding to ensure you meet all local requirements.

A final thought...

Rooftop rainwater harvesting is a simple and effective way to conserve water. With proper planning and design, a rooftop rainwater harvesting system can provide a cost-effective source of water, either for non-potable applications, potable supply to your house, or supplementary supply. It should be a priority strategy for many households when considering their water efficiency and conservation options. 

We have a great tool for calculating how much rainwater you can harvest from your rooftop. Take a look at our Rooftop Rainwater Harvesting Calculator.

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