Q:  Which is the right water tank for your family?

A:  Plastic or polyethylene has been developed and tested in the market place over many years for the manufacture of upright water storage containers.  It cannot rot or corrode, and is UV stabilised for Australian & New Zealand conditions.  Water tanks made from polyethylene are available in a range of sizes and designs to suit your needs and to make an attractive addition to your home.

If you�re ready to go out and buy a tank, here�s some information to help you make the right decision for your home.

First, take a look at the rainfall in your area either by checking out the local Bureau of Meteorology website.  You will need to know the approximate measurements of your roof and finally you�ll need to work out roughly how much water your particular household uses and how much of that you want to replace with rain water.

Government guidelines differ between local authorities and some will have specific rules about whether tanks can be used for;

• Supplying the entire house (mainly in rural area)
• connection to toilets and the laundry
• watering the garden.

Most rebates and subsidies rely on tanks being installed and connected to the home, so make sure you check this out before you decide on your tank size and its installation.  Finally you�ll need to decide what type of tank best suits the space you have available.

Above the ground cylindrical tanks come in straight wall or corrugated sides. There are various models of narrow tanks available that can;
- fit under your eaves,
- be used as fences or walls in outside areas and
- if space is an issue, there is also a range of in ground tanks available.

Round tanks are far more economical but, they generally take up more room.  If space is a limiting factor, look at the slimline range as they are generally taller but will also normally fit down the unused side of the house.
Source: www.watertanks.org.au A Division of Association of Rotational Moulders Australasia Inc

Q:  What do I need to consider before I buy a rainwater tank?

A:  As a rule of thumb try to select the largest possible tank capacity for the available area.  In rural locations, space is not always a problem and so a traditional round tank is usually the most cost effective solution.  However, in residential areas space can be a real problem, particularly if you are limited to locating the tank down the side of a house or in a small back yard and so a Slimline tank may be more practical. 

Before making your final decision consider the following points:

• Carefully measure the space where you are going to place the tank.  Don�t be afraid to ask some one to help with the measurements as it is critical to get them right.  A mistake with the measurements can prove costly later on.  Measure the available width allowing sufficient space for a person to pass between the tank and the fence once it�s installed.  Measure the available length, checking to make sure the tank won�t obstruct doorways, windows or external air conditioners tree trunks or other obstacles.

• If sitting the tank next to the wall of the house, measure the height under the eaves to ensure you have plenty of room to fit the tank.  Remember to leave sufficient space between the eaves and the top of the tank so you can connect the tank to the spouting with an appropriate filter and first flush devise (if required).

• If you are connecting the tank to the toilet, try and locate the tank next to the down pipe closest to the toilet.  This will reduce the amount of piping required and help keep your plumbing costs down.

• Having decided where to locate the tank, work backward form the site to your front drive checking to see if you have room to move your tank to its desired location.  Check for narrow paths, gateways, outdoor obstacles and overhead obstructions. You may need to reduce the size of your tank to ensure it will fit.  Remember, provided you have sufficient space, you can always join a couple of smaller tanks together to increase your capacity.

• Will you be connecting a pump to the tanks or use gravity/buckets to water your garden?  A pump should be fitted by a qualified tradesman and will require a weather proof external power outlet to be installed.

Q:  How do I decide on the right tank for my needs?

A:  This is a tough one and depending on the application you will need to consider a number of factors.
For example:

• The amount of water you currently use*.
• The number of people in your home*.
• What you would like to use the rainwater for.
• The rainfall in your area.
• The size of your roof.
• The size of your garden,

Q:  How can I calculate how much water I currently use?

A:  Use the following table as a guide to calculating your average weekly water consumption. 

• For example an average 2 person household with garden would use approx 4,760L of water per week.

NB: The consumption rates detailed above are averages per day and are indicative only.

Q:  How much water can I collect from my roof?

A:  The amount of rainwater you can collect is dependant on a number of factors including:

• The area of your roof.
• Average rainfall in your area.
• The number of down pipes connected to your tank.

The formula to bear in mind when calculating how much water you can collect is this;
One millimeter of rain falling on one square metre of roof (1m x 1m) will collect one litre of water.
To make this calculation work you need to understand how much rainfall you are likely to receive in your area per annum.

Table 2. gives you the average rainfall for Australian capital cities.  For rainfalls in other cities and towns go the Bureau of Meteorology website at (http://www.bom.gov.au/climate/averages/).

Source: http://www.bom.gov.au/climate/averages/ 

For the sake of this calculation let�s assume you live in Brisbane and your house has a 200 square metre roof area.

Therefore the calculation becomes 200 (roof surface area) x 950 (mean average rainfall for Brisbane) = 190,000 (potential amount of water in litres captured by your roof over a 12 month period).
Assuming you will have one down pipe feeding into your tank, the last part of this equation is to divide 190,000L by 4 (assuming you have four down pipes serving the roof and all provide an equal supply of rainwater) = 47,500L.