rainwater spilling off tin roof

Rainwater harvesting involves the collection, storage and distribution of rainwater from a surface (often a roof) in order for it to be used. In the past, rainwater collection fell out of favour because tanks became breeding grounds for insects, sparking concern about water contamination. However, these days, modern rainwater tank installations that are regularly maintained have reduced these risks considerably. Here are some reasons why you should consider harvesting rainwater.

What are the benefits of rainwater harvesting?

Significant social, economic and environmental benefits can be achieved by using rainwater, and in fact, rainwater harvesting is the most accessible source of water in Australia. Everyone who lives in an urban area continues to enjoy rainfall, and harvesting rainwater can provide water long after natural catchments dry up.

In urban areas, rainwater harvesting also reduces the costs of water infrastructure. Desalinated water relies on an electricity network, and the cost of supplying mains or reticulated water services is becoming more expensive every year. Water distribution systems like dams, pipes and treatment plants also need to be constructed, and ultimately as rate (and tax) payers we foot this bill.

Taking responsibility for your own water supply can help ease the burden on your town water supplies, significantly reduce your water bills, and harvesting rainwater can also help the environment by reducing the negative impacts of stormwater run-off on our creeks and water habitats.

Is rainwater safe to use?

Rainwater is a safe and sustainable water supply if it’s captured, stored and dispensed correctly. In fact, some people argue that rainwater is actually safer and healthier than water that’s supplied through our mains. This is because mains water is normally stored in dams and treated with chemicals to eliminate bacteria and make it safe, and then it’s pumped back through a network of pipes throughout our community.

How can rainwater be used?

There is no higher quality water source available to us than rainwater, and rainwater that’s collected and stored appropriately represents a sustainable source of water. This can be used for a variety of purposes inside and outside the home, from toilet flushing and doing laundry to watering the garden and other outdoor activities.

It’s also an environmentally conscious choice because harvesting rainwater and using it for these uses can reduce mains water requirements in a typical household by up to 70%. If your hot water system also takes advantage of rainwater, then the reduction can be as high as 85%!

What’s a typical rainwater harvesting system?

An active rainwater harvesting system usually consists of:

  • A collection surface – usually an impermeable surface, like the roof of a home.
  • A conveyance system – which includes downspouts and gutters that lead the water from the collection surface to where it will be stored.
  • Filters and diverters – these keep leaves, debris and other unwanted particles from entering the water storage tank.
  • Storage container – this can be a watertight, underground or aboveground water tank and these can vary in size, shape, size and composition depending on your needs and the available resources. However, it should be light, animal and insect-proof.
  • Water treatment – depending upon the intended use for your water, it can consist of carbon filtration, drip irrigation and other treatment techniques.
  • Distribution system – this is what transports the water from the storage container to where it will be used, and it can be powered by a pump or simply by gravity.

Rainwater tank systems can also be installed using a variety of different configurations, including:

  • Tanks installed above or below the ground
  • The use of pressure or gravity systems
  • The use of dual water supply systems
  • The inclusion of a detention volume inside the tank for additional stormwater management

What does the Council recommend in terms of rain harvesting systems?

Many government departments and industry associations have developed or are developing guidelines for the use of rainwater harvesting systems. These will ultimately help optimise water quality, and the main aspects of many of these guidelines are:

  • Incorporating gutter mesh systems – to help ensure gutters don’t become blocked with debris and leaves and to prevent mosquito-breeding habitats.
  • Installing rain heads at gutter downpipes – to separate debris and leaves from the flow of water and to keep mosquitoes out of the pipe systems that lead to the tank.
  • Preventing the ‘first flush’ of rainwater from entering the tank – to reduce the amount of roof pollutants.
  • Insect-proofing all tank openings (the inlets and the overflow outlets) – to prevent mosquitoes breeding.
  • Regular maintenance of the tank, roof and gutters, catchment system and the inlets – to ensure a safe supply of water.

How much does it cost to install a rainwater harvesting system?

The upfront cost will depend on the type of system you choose and the variety of elements involved. For example, if you only require rainwater for toilet and outdoor usage, you might only need a pump, rainwater tank, and a leaf diverter.

Alternatively, if you are wanting the system to supply the above as well as the laundry and hot water usage, then you might need the above as well as a first flush device to remove sediments, and an inline filter and UV disinfection system on the drinking water supply line.

There will also be electricity costs if you decide a pump is going to be a part of your system, and ongoing maintenance. Rebates however are available from Australian local, state and territory governments, and they depend on the volume of your tank and what you’ll use the water for. For more information about rainwater harvesting systems, visit the Australian government’s website.

How do I go about starting the process?

The first step towards implemented a rainwater harvesting system is to evaluate the site. You need to know where rainwater drains, flows and pools around your property. You also need to know the boundaries and size of your property and the location of electric lines, sewer lines and other utility lines. Then you need to determine where you storage tank will be located, which will help you work out how and where you’ll integrate a rain harvesting system into your property.

The next step is determining the type of components you’ll need for the type of system you want to implement. This involves considering the tank size, its location, the quality treatment methods, the size of your collection surface and the method of distribution.

Once you’ve decided on all this, it’s time to select a suitable installer who is experienced, licensed and is aware of the installation requirements.

Considering installing a rainwater harvesting system but need some advice? Contact Yarrow Plumbing today on (07) 3277 5742.