Other Tanks

Zincalume is the cheapest tank available. Although the tank manufacturer may give a one-year warranty on the workmanship, there is no warranty on the material. A Zincalume tank will generally corrode to perforation within eight (8) years, with some only lasting four (4) years. As the saying goes, "You get what you pay for". This will be the most expensive tank you have ever purchased. Your initial investment for a  22 000 l ( 5000 gal ) Zincalume tank will be about $1,700.  With a service life of around eight (8) years, this tank will depreciate $212 per year. There will then be additional expense involved in removing this tank.

Pic Taken:
Jan '05

Aquaplate  ( plastic coated steel ) is a major improvement on Zincalume. However, one of the  disadvantages of this material is that any microscopic penetrating scratch to the plastic film is enough to initiate corrosion.  Microscopic scratches can occur during the manufacturing process, or during cleaning or servicing.  Therefore, to effectively service or clean an Aquaplate tank, extreme care must be exercised when working inside the tank,as a matter of fact entering the tank will void the warranty of the tank.  In addition, the coating is not UV stabilised, and is very sensitive to sunlight and heat, the Bluescope datasheet for Aquaplate states that temperatures over 70 degrees have to be avoided. This makes Aquaplate the most sensitve tank to bushfire exposure, regardless what some manufacture state,  exposure to  external heat such as a grass or bush fire, will destroy the coating and render the tank useless. The manufacturer's warranty on this product is for twenty (20) years. On face value, this is a reasonable warranty. However, the warranty has numerous conditions and requires close attention before assuming a claim for premature corrosion or manufacturing faults would be successful.  For a 22 000 l Aquaplate Tank you pay approximately $2,600. Assuming a service life of twenty years, it will depreciate $130 per year.  There will then be additional expenses involved in disposing of it.

Poly (Plastic) tanks seem an attractive alternative to steel tanks.  They do not corrode; they come in a variety of colours, and the majority have a twenty-five (25) year warranty. However, these tanks are manufactured from petrochemicals derived from oil, and are difficult to recycle or dispose of in a safe and ecological manner.   Being constructed from such materials, a plastic tank is also highly vulnerable to damage from fire.  In addition, the wisdom of storing drinking water in a container made from chemicals is yet to be proven.  Another major disadvantage of a plastic tank is its ability to absorb heat and raise the temperature of the water.  Warm water encourages the growth of algae, supports bacteria, and tastes unpleasant.  Plastic tanks have only been in production for about ten years, and as the effects of exposure to intense prolonged sunlight are known to break down the UV stabiliser, a plastic tank will inevitably fade in colour and may collapse or split.  Consideration should also be given to whether the warranty on a plastic tank is transferable with the sale of a property.  A  22 000 l plastic tank costs about $2,500. Assuming a service life of twenty-five years, it will depreciate  $100 per year.  There will then be further expenses involved in the ecologically safe disposal of the tank.

Extracts from a recent Tanks Direct brochure:

"Tanks Direct tanks have a fully self supporting roof.  Some tank manufacturers have a pole or frame in their larger tanks to hold up the roof. These poles sometimes pushes through the top of the tank (or even the bottom) and allow vermins to get into the tank. Another important feature of our range is that our mould join line is in a horizontal position and the top of the tank, where there is no water pressure, insuring that there are no potential weak points.  The mould join lines in some other tanks are in a vertical position which runs all the way down to the side and across the bottom of the tank where there is a maximum water pressure.This can cause the tank to split or crack.  And finally a story from the same brochure, a new customer of Tanks Direct has recently phoned another company to purchase a tank and was not told that the lid was cut off and have been put back on with screws to save on transport. When he received the tank, it was in good order and came with a 25 year guarantee. But after about 6 months of being in the sun,the plastic started to come apart between the screws at the top of the tank. The customer then noticed a frog pulling its leg into the top lid where the screws have come apart. When he opened the manhole to inspect the tank, he found 28 frogs in the tank, not to mention mosquito larvae. He phoned the tank company to report the problem and asked about his 25 year warranty,but was told that this did not include the lid coming apart at the top or for having a cut lid in the first place.

"It makes you wonder how many faulty plastic tanks are in the field if one manufacturer can point out so many faults on plastic tanks."

Update12/6/08:There is now hard scientific evidence emerging which questions the suitability  of plastic (poly) as suitable material for potable water tanks. Phthalates (plasticisers), which are water soluble,are leaching in minute quantities into the water.Recent research indicates that the minuscule quantities of Phthalates, previously thought to be irrelevant, are effective endocrine disruptors in the human body. For more information request your free DVD (Phthalates, effect on the human endocrine system) by mailing a stamped and self adressed envelope to Po. Box 16, Cannon Hill, 4170  

Update 24/10/08: Further scientific evidence questioning the suitability of plastic in the human food chain: click to read a USA Today article.

Concrete tanks come in two qualities - good and "not-so-good". A good quality 5000-gallon concrete tank will cost about $3,500 and will have an expected service live approaching that of stainless steel.  Of course, it will not be as hygienically clean as stainless steel, and lime will always leach into the drinking water, but it is difficult to fault a good concrete tank further.

A "not-so-good" concrete tank will cost about $2,400 and may have a service life as short as ten years before cracking and concrete cancer render it obsolete.  Concrete tanks are notoriously difficult to repair. 

A good 5,000-gallon concrete tank will cost approximately $3,500. Assuming a service life of forty (40) years, it will cost $87.50 per year. You will then have to pay to have it demolished and removed.  This is generally a very expensive process.

Stainless Steel - A 5,000-gallon Stainless Rainwater Tank has a service life well in excess of forty (40) years and will add value to any property.  A stainless steel tank will depreciate $67.50 per year over this period, and is the only tank which can be fully recycled. When a stainless steel tank reaches the end of its effective service life, possibly in 50 to 60 years, it will be worth a considerable amount of money as scrap metal.  Given the rate of inflation and the constantly escalating cost of raw materials, this tank may be worth more as scrap metal than its original cost. Consider this example, take a new 20000L zincalume, aquaplate, plastic, concrete and stainless steel tank and squash each of them into a block:

Zincalume - you pay for the removal

Aquaplate - as above

Plastic - will be a real problem to dispose

Concrete - you end up with a truckload of rubble which you may be able to                 use as fill.

Stainless Steel - any scrap metal dealer will happily pay you $500.00 (in 2006) to take the stainless steel away.  You only can speculate the value in 2050.