Rainwater Harvesting for Owner Builders

As an owner-builder, you have the unique opportunity to design your project with sustainability and long-term cost savings in mind. One of the simplest yet most impactful eco-friendly features you can incorporate is a rainwater harvesting system.

By capturing and storing rainwater, you’re not only reducing your reliance on mains water but also creating a resource that can enhance your garden and lower your utility bills. Here are some considerations and ideas to get you thinking.
Choosing the Right Tanks

Rainwater tanks come in various shapes, sizes, and materials. Your choice will depend on your water usage goals and available space. For smaller properties, slimline tanks or underground options can save space while still providing significant water storage. If you have more room, traditional round tanks might be the most cost-effective choice.
Consider the material of the tank as well. Plastic tanks are lightweight and resistant to corrosion, making them ideal for coastal areas. Metal tanks, often made from galvanized steel, are durable and aesthetically pleasing, while concrete tanks offer excellent durability and temperature stability for underground installations.
Ideal Locations for Your Tanks

Where you place your rainwater tanks will affect the efficiency and usability of your system. Ideally, they should be located close to downpipes to minimise the need for additional plumbing. The ground must be level and capable of supporting the tank’s weight when full, which can be substantial (1 tonne per 1000 litres of water). If possible, situate your tanks in shaded areas to reduce water temperature and limit algae growth.
Think about aesthetics and accessibility as well. Tanks can be camouflaged with landscaping or fencing, but ensure they remain easy to access for maintenance and cleaning. Underground tanks are a great option if you prefer an unobtrusive look. These may cost a little more but are a great option if funds allow. Consider the ability for road traffic etc and access to areas that may be affected by the tanks location. These factors will impact the cost.
Filtration and Maintenance Requirements

Clean water is critical, especially if you plan to use your rainwater for drinking or household use. Installing a good filtration system will ensure your water remains safe and clear. Basic systems start with a leaf diverter to keep out large debris and progress to first-flush diverters that prevent the dirtiest runoff from entering the tank. For potable water, additional filtration such as Carbon cartridges, UV sterilisation or reverse osmosis may be necessary.
Don’t forget ongoing maintenance. Regularly inspect and clean your gutters, downpipes, and filters to keep the system functioning optimally. Schedule periodic checks of the tank itself for any signs of wear or contamination.
A poorly maintained filtration system can quickly result in water of a lower quality than unfiltered water.

Benefits for Your Garden and Lawn

Your Owner Builder project will certainly reap many benefits from an effective rainwater harvesting system. One of the most rewarding uses of harvested rainwater is keeping your garden lush and healthy. Rainwater is naturally free of the salts and chemicals found in mains water, making it ideal for plants. By using a drip irrigation system connected to your tank, you can water your garden efficiently, even during dry spells or water restrictions.
For larger properties, harvested rainwater can also be used to maintain lawns or even fill ponds and water features, creating a beautiful and sustainable outdoor space.
Maximizing Your System’s Potential
To get the most out of your rainwater harvesting system, plan for future needs. Will you want to expand the system to include more tanks or integrate it with greywater reuse? Thinking ahead during the design phase can save you time and money later.

For those owner builders constructing in a Bush Fire Zoned area, it may be possible to have the additional benefit of storage for the purpose of fire fighting. This will of course never replace a well designed property that is compliant with all mandatory legislation, however it may just add a little extra protection and enhance your fire resistant capabilities. Consult with an expert in this area.
In Closing

Owner builders must check your local regulations. Many councils encourage rainwater harvesting and may even offer rebates, but there could be specific guidelines you need to follow.
Integrating rainwater harvesting into your owner-builder project isn’t just about saving water; it’s about creating a sustainable home that works in harmony with the environment. By carefully choosing your tanks, planning their location, and ensuring proper filtration and maintenance, you can enjoy the many benefits of rainwater harvesting for years to come. Plus, your garden will thank you for it!
So, why not make rainwater harvesting a key feature of your next project? It’s a decision that will pay dividends for both your wallet and the planet.