When purchasing a Rainwater Tank as your primary water supply on a Rural property, here are the facts that you need to consider:

The safest drinking water for your family. 

The health reasons why you should choose an Inground Concrete Rainwater Tank over a Plastic Tank.

Rainwater is naturally acidic and a healthy diet should be slightly alkaline.  Rainwater stored in a plastic tank remains acidic. On the other hand rainwater stored in a Concrete Tank which is naturally alkaline will neutralise the acidic rainwater.

Please read the following article in relation to the acidic rainwater stored in plastic Tanks:

“Copper poisoning linked to plastic water tanks” published 26/11/10 by the ABC.

view article on abc

Sunlight and heat will turn water off.  It promotes algae and bacteria growth which can cause ill health in many ways.  The water stored in a plastic tank will be affected by both sunlight and heat. Also with the plumbing connection of an above ground plastic tank, the downpipes are  in the sun with water left lying there, sometime for weeks if there is no rainfall.  This will promote algae growth the quickest.

The water in an inground Concrete Rainwater Tank is kept cool and dark below ground and in our case in 125mm thick concrete walls, so no algae will grow.  Also the downpipes go straight down into the ground and all the plumbing is concealed underground. No water will be left sitting in pipes.

What size Tank to I need?

Coffs Harbour City Council and most other shires require that you have a minimum of 45,000 litres of potable water for household use.  The Rural Fire Service also require an additional amount of 10,000  – 20,000 litres (the amount depends on the risk) to be kept in reserve.  This water can be stored in the same tank, with the foot valve being kept high enough off the floor, ensuring that the water for the Rural Fire Service is always kept in reserve.

On average a family of four will use approximately 4,500 litres of water per week in the home.  Higher water usage if they wish to water gardens/lawns and top up pools etc.

Considering the Council’s and RFS requirements and the average family’s water consumption, this makes our 90,000 litre Rainwater Tank the obvious choice for most.

Some people in smaller households may think then that they do not require such a large Rainwater Tank, however, if resale is a factor, a family may be put off by an inadequate water supply.

How much Rainfall does it take to fill a 90,000 litre Rainwater Tank?

The simple equation is; for every 1 square metre of roof area and every 1mm of rain, you catch 1 litre of Rainwater.  Coffs Harbour’s average annual rainfall is approximately 1600mm and an average roof of a four bedroom home is 250m2.

Based on these averages the equation is as follows:

1600mm x 250m2 = 400,000 litres

Effectively, this means you can refill a 90,000 Rainwater Tank four times in a year.  The problem though, with a Rainwater Tank less than 90,000 litres is, that during certain weather cycles ie. El Nino (which can last for years at a time) it can go for months at a time with minimal or no rainfall at all.

These dry weather patterns are frequent over a ten year cycle and should not be forgotten during periods of higher than average rainfall, as we have experienced since 2009.  The dry weather periods will return and you can be confident with a 90,000 litre Rainwater Tank that you will have an adequate water supply that will last a family of four (with an average consumption) for a period of at least 5 months.  Longer is the water is used more conservatively.

The other benefits of installing a 90,000 litre Coolamon Concrete Tank.

Additional to water quality, one of the other obvious benefit of a Concrete Tank is its strength and reliability (that is of course if the Concrete Tank builder has a proven fail proof method of construction, not all do!!).

Our 90,000 litre inground Concrete Tank has a surface area that is 7700mm in diameter, approximately a 50m2 surface area which can be utilised for other purposes. It can be incorporated in your outdoor living space with a Gazebo on top, used as a slab for a shed, used for your clothes line, a turning circle off the driveway (where space is an issue) etc.  The options are endless and there is a huge cost benefit of having a readymade 50m2 concrete slab for your use.

The Tank is also 2300mm high and if sitting above ground would be the size of a double garage which I think you would agree is an eyesore (particularly in the case of multiple above ground plastic tanks).

Rainwater is a Precious, yet sometimes undervalued resource which can be overlooked when building a new home on a rural property.  Understandably people would rather spend money on things like a home cinema for example, but consider this:

You have a smaller inadequate Rainwater Tank. It’s our second year of an El Nino weather pattern, we’ve only had 156mm of rain in 5 months, you’re having a shower and you’re all lathered up and the water stops running.  It’s dry, so other people with inadequate water supplies are now buying a load of water (10,000 litres @ $200) every 14 days. The water carries are so busy and working 18 hour days but the waiting time for a load water is still up to 10 days.  This happened in Coffs Harbour in 2002!

Add to this scenario that the surrounding habitat is so dry a bush fire could start at any time and you have a limited amount of water left or even worse, you have a plastic tank which has just melted as the fire approaches!!

Australia is the driest inhabited continent on Earth.  Have Water security with a 90,000 litre Coolamon Concrete Tank and also peace of mind that you have the safest drinking water for you and your family.

The specifications of our standard medium duty 90,000 litre Tank, at a glance:

  • Diameter – 7750mm
  • Depth – 2270mm
  • Walls, floor and lid – 125mm thick
  • Concrete – 32mpa & Vibrated
  • Floor and Lid Steel – F82 (Double layer in lid)
  • Wall steel – F818
  • Piers – 6 x 125mm
  • Manhole – 450mm x 450mm

If Passenger vehicle traffic is required then the 6 piers are increased to 225mm.

Also we have a Super Heavy Duty Tank designed to carry a W8 (8 tonne) wheel load if required.

We can Engineer design a Tank to suit any requirements.

  • Over the past 12 years that I have been cleaning tanks, I have cleaned dozens of Coolamon Tanks. They are well built and I have not had to repair any of them.  Other tanks are roughly made in comparison and I have had to repair dozens of other tank builders tanks each year.  As an added bonus there is no algae to clean out of a Coolamon Tank unlike plastic tanks.

    Steve Millward

  • We recently contacted you and requested the design and engineering details of the

    two water tanks Coolamon built on our property in 1989 and 1991. Thank you for providing us with the relevant Engineer’s drawings and specification. lt is pleasing to know that we could still contact the company that built our water tanks over 20 years ago and source the information we needed.

    Mr Howe

  • I must say we have been very happy with the whole process from the quoting to the finalization of the tank – we do appreciate the wonderful service so thankyou to Richard.


  • I just need to say that you are the best business I have ever dealt with for both your caring and your prompt customer service.

    Richard not only did you give up your valuable Sunday time to assist us in our need, but you refused to accept payment for the task and parts you supplied. I was happy to pay but now the only way I can show my gratitude for your excellent service is to write this email and offer you my sincere

    thank you to you and your family from the bottom of my heart. You are good people.

    Warm regards

    Jane & Trevor Butcher

  • Great approach to the job, excellent procedures in place for construction and the best OH&S system on this site.


  • Fantastic to watch – know their trade backwards.


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Contact Us

PO Box 6478 Coffs Harbour, NSW, 2450

Phone: (02) 6653 7357

Fax: (02) 6656 4008

Mobile: 0427 400 292

Email: info@coolamontanks.com.au