Rainwater Tanks - Why Save Water?

Few people realise that only 3% of water on earth is fresh water suitable for drinking. 2% of this is locked in polar ice caps, which means only 1% is available for everyday use.

Australia is the driest inhabited continent on earth and we are also the greatest consumers of water per person in the world. Global weather patterns are changing and there's little doubt that in the future Australia is likely to get hotter and drier. In recent years, the long-lasting drought in many parts of Australia has resulted in widespread water restrictions.

In The Hunter every home uses about 210,000 litres of water a year with every person using about 205 litres every day. A rainwater tank can collect around 80% of the rain that falls onto the area of your roof which is connected to gutters and downpipes. That's about 40,000 litres of water.

In the past, rainwater tanks were a common feature of the Australian landscape, but they've almost disappeared from cities and suburbia.

Rainwater is a natural and free source of fresh water which can be used use for a variety of outdoor and indoor purposes, such as watering gardens, washing cars, flushing toilets and washing clothes. Using rainwater for domestic purposes can not only save precious drinking water, it can also help you to reduce your water bills.

Not many people are aware of greywater and how it can be used. Greywater is waste water from domestic plumbing such as showers, basins and taps (non toilet fixtures). Greywater can be collected and used for outdoor purposes, like garden watering. And treated greywater can be re-used indoors for toilet flushing (saving approximately 50 litres of water a day – that's equivalent to 6 buckets of water) and clothes washing (saving approximately 90 litres of water a day).

If you're thinking about installing a rainwater tank or greywater system have a quick look at the information below. We've tried to simplify the mass of information in the market to help you decide which tank and type of installation best suits your needs. And if you've already decided upon the tank you want, but are interested in details of government rebates and the savings you can make, just click here.

What rainwater tanks are available?

Rainwater tanks are no longer just huge, round and ugly: they come in all shapes and sizes to suit the urban and suburban home. There are three main types you may want to consider:

  • Above ground rainwater tanks are usually the cheapest. There are many shapes available to suit your home, such as slimline and wall line tanks which can fit tight narrow spaces.
  • Underground rainwater tanks save on space and have greater catchment potential than above ground tanks. However, these tanks can be more expensive and installation usually requires excavation. You'll also have to arrange for an annual check of the backflow prevention devices. And if you're building a new home consider underground tanks that can be fitted into the slab.
  • Underfloor bladders save on space and can have greater catchment potential than above ground tanks. However, installation is more involved.

Consider the type of material

Tanks are available in various types of materials, the most common are plastic (polyethylene), concrete and galvanised steel. To help you decide you may want to consider the following:

  • Galvanised steel

    This is the most common and cheapest tank material in Australia.

  • Concrete tanks

    strong and long lasting. These are typically constructed on site and can be designed to specific sites.

  • Plastic tanks

    are available in a range of sizes and colours. Tough, durable and lightweight, these innovative systems are available in types such as storage walls and bladders

Remember, the type of material you choose for your tank will depend on your budget, your required tank capacity and water use.

What size tank will I need?

Before you can decide upon the size of rainwater tank to buy you'll need to consider how you plan to use the collected rainwater.

Will the rainwater tank be for outdoor use only or indoors as well? In general, the average household requires a tank with approximately 2,000 to 4,000 litres capacity to water their garden year round. This will cost approximately $1,000 to $2,000, including installation. But remember there are government rebates available.

And if you're planning to connect the tank to your home's plumbing for use in the washing machine and toilet flushing, you'll need a tank with a capacity of over 4,000 litres.

If you're purchasing a rainwater tank for your home's sole water supply, then you will need a tank with a capacity of 50,000 to 100,000 litres. This will cost approximately $6,000 to $8,000 including installation and delivery. The most economic large tank is normally a concrete tank built on site.

Click here to check the rebates available as they vary with size of tank and intended usage.

You'll also need to look at the area of your roof to determine if the water captured will be enough to meet your needs.

A Few Things to Consider

If you want to use rainwater for toilet flushing, washing machines or any other indoor use, you will need a licensed plumber to connect the tank to your mains water supply. When connecting the tank to your mains water supply you will need a backflow prevention device attached to your tank. This prevents contamination of the mains supply if the water pressure changes suddenly and the water flows backwards.

If you are interested in installing a rainwater tank, contact your local council or Hunter Water (you'll find details in our Eco Directory) to find out which rules and regulations apply to your local area. Click here to go to the Together Today Eco Directory for all your contact details.

Greywater Systems

Greywater is the waste water from showers, baths, spas, handbasins, laundry tubs and washing machines. This water can be collected and treated for use in the garden. Thus reducing your water bills.

There are two basic types of systems to recycle greywater: diversion devices and treatment systems.

A diversion device can be as simple as attaching a flexible hose to your washing machine outlet to collect rinse water to more sophisticated diversion systems which may include a surge tank, filters and a pump.

Pros

  • cheap and easy, however price for the more complex greywater diverters range from several hundred to several thousand dollars.

Some considerations:

  • the water is untreated and should be used with care
  • damaging salts and chemicals can kill plants and ruin the soil
  • run-off can escape boundaries and create problems for neighbours
  • not suitable for watering vegetable gardens, especially if food plants will be eaten raw

Treatment systems collect and treat (and some disinfect) the water to various levels of purity and hygiene.

Pros

  • Will reduce your mains water consumption and if teamed up with a rainwater tank can save you even more water
  • Safer water - pathogens and unwanted chemicals (such as salts and nutrients) can be removed from the water, including mirco-organisms and chemical treatment.
  • More options for reuse, appropriately treated water can be used on vegetable gardens.
  • Personal source of water for domestic purpose in times of water restrictions

Some considerations:

  • Expensive, basic systems cost around $4,000. Systems that treat greywater to a level which is considered safe for watering plants intended for eating, but not for drinking or preparing food, cost from around $10,000 up to well over $20,000 including installation.
  • Requires regular maintenance

Contact your local Council for a list of treatment systems accredited for use in your area.

How to Keep Saving

The State and Federal Governments are offering rebates for the purchase and installation of rainwater tanks and greywater systems. For details of this rebate simply click here.

To help Australian families with the cost of installing water saving and energy efficient products the Commonwealth Government is offering interest free Green Loans of up to $10,000. A Green Loan does not affect or make you ineligible for any available Government Rebates. To find out more about Green Loans click here.

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