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Can I reuse stormwater in the suburbs?

Did you know that one-third of the water you use in your home is flushed down the toilet? That is a lot of money to see spiral down the drain. Collecting your rainwater for household and garden use can reduce your water bill drastically.

Not only will you save money, but you will also be helping to protect the environment. Stormwater eventually ends up in waterways and the ocean. This can cause potential erosion and flooding, as well as carrying pollutants picked up on the way.

If you can divert and capture some of the precious water that drips off your roof and rushes down your driveway, it can be reused in a variety of ways. Anything from flushing toilets and filling washing machines to watering gardens and washing the car.

Here’s how you can do it...

Collecting and reusing roof water and stormwater

To use your roof as a collection area, all you need is some spouting and pipes which lead to a rain barrel or tank. The level of complexity from there depends on how much water you plan to collect, and what you want to use it for.

If you are merely after a small system that can water the garden and wash the car in summer, you can just rely on gravity and buy a smaller barrel or tank to pop on your property. However, if you are planning to direct the water into your house and want to use it for drinking and showering, you will need to look into a slightly more complex system. This system will probably require building consent from your local council - as well as a plumber.

Rain barrels and tanks

Storage tanks come in a variety of sizes to fit even the most cramped property. They can be installed above or underground. If you are collecting for your humble garden, you will probably be fine with installing a 200-litre barrel with a tap or hose connection.

But, if you are planning to use the water indoors (in addition to a mains supply), look at installing a 5000-10,000 litre tank. One thing to keep in mind is that in some regions, tanks over a certain size and in certain locations may require resource consent.

Remember that water is heavy, so even a small tank will need to be very well supported.

Here are some of the extras you will need for correct installation:

  • A water pump,

  • A water filter and/or treatment device,

  • Leaf guards and screens in the gutters and downpipes,

  • A first-flush diverter to push that first gush of rainwater away from the tank (which usually contains a lot of debris),

  • A backflow prevention device to prevent rainwater from entering and contaminating the mains supply.

Potable Water

Once you decide you want to reuse your roofwater for bathing and drinking, you need to consider the materials and paint used on your roof, in your pipes, and the tank itself. This will ensure your supply isn't contaminated. To ensure your water isn’t contaminated, you will also need to invest in a high-quality filter or treatment system.


From a basic barrel to a full-on, property-wide system, there are a variety of ways to reuse your roof water and stormwater. Like many things, the more complex the system, the higher the cost. And you will potentially need to factor in building consents and annual inspections.

Every council has their own guidelines surrounding the collection and use of rainwater and stormwater, so you will need to check out the regulations before starting any work.

Disclaimer As with all our blogs, the information detailed here is general in nature and meant as a preliminary guide only. This should not be substituted for your own investigations or use of your own professional’s. Planning Plus is not liable for any errors or omissions.

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