No, stainless steel is not affected by concrete, unlike other steel tanks.

Q: When I lift the inlet strainer on my tank a cloud of mosquitoes emerges.Where are they coming from? All the mosquito screens on my tank are in perfect condition!

This must be the most frequently asked question, and unfortunately there is no simple answer or solution.Firstly, it must be emphasised that this problem commenced with the introduction of rain water tanks, and is by no means a new problem. The consumption of rain water tainted with "wrigglers" presents no health hazard, but can be easily prevented with the installation of a 20 micron filter after the pressure pump. Ensuring that the tank remains free of mosquitoes, wrigglers and larvae is proving to be more difficult.The assumption that the mossies somehow get through the screen is wrong, "around it" would be the more appropriate term.Most inlet strainers do not make a perfect seal on the tank. This is true not only on steel water tanks, but also on plastic tanks particularly when the sunlight starts to buckle the plastic.A 2-3mm gap between the strainer and the tank seem insignificant, but is plenty big enough to let female mossies  enter the tank and lay eggs.We developed a screwed inlet strainer which seals perfectly and allows no gap between the tank and the strainer. Unfortunately this strainers are custom made and therefore rather expensive. The second way for mosquitoes to enter the tank is much more difficult to seal. Roof guttering will always retain small paddles of water after a rain event. This is the perfect place for female mossies to lay their eggs, which of course are washed into the tank with the next rain.The 0.98mm aperture of the inlet strainer is far to coarse to catch microscopic eggs, which pass without difficulties into the tank to hatch. At the current stand of rain water harvesting technology there is only one accessory available to ensure your tanks remains free of any mosquito larvae and other contaminants. Please visit www.sealedtanksystem.com for more information.

Q: My polyethylene tank has a UV rating of 16,what does it mean?

All polyethylene's are susceptible to degradation upon long term exposure to sunlight.  This deterioration is brought about by chemical changes which occur in the polyethylene as a result of exposure to the ultraviolet  (UV) portion of light.  The poly becomes brittle and loses strength. To slow down this process UV stabilisers are added to the polyethylene. The number indicates the amount of stabiliser added to the poly. For example: UV 4 would mean 4000 hours of continuous outdoor exposure in Florida, before the polyethylene loses 50% of its original strength.  Consequently, UV 16 (this is the maximum amount of stabiliser which can be added) would mean that the poly will last 16000 hours before it loses 50% of its original strength. After this time the poly is spent, and no amount of welding or other repair methods will prolong the service life of your plastic tank.  Currently, there is no way to recycle the spent plastic and this may create a real environmental problem when all the plastic tank will start to fail in the years to come. Numerous tanks which were built with a UV rating of less than 16 are failing now. It is a fair assumption that the UV exposure in Queensland is similar to Florida, if not worse.

Q: I hear comments that plastic tanks leak hormones (estrogen) into the water. Is this true?

We are aware of these rumors but so far scientists failed to uncover  evidence supporting this claim. But it is appropriate to point out in this context, an article published in the Brisbane Courier Mail (dtd 13/03/06) about contaminated water caused by storage in plastic bottles.  The article refers to a study conducted by Dr.William Shotyk, Director of the Institute of Environmental Geochemistry at the University of Heidelberg in Germany. Dr. Shotyk found that a chemical called antimony continously leaches from the plastic bottle into the bottled drinking water. This study is of major concern if you take in consideration that PET (Polyethylene Terepthalate) bottles were considered absolutely safe for over 15 years. (research google:shotyk)The unavoidable conclusion is the question,  Is it only a matter of time before another study determines that water stored in plastic tanks is not as safe as we were made to believe?

Update 25/4/08: Brisbane`s Channel 10 news on the 16/4/08 reported that plastic baby bottles leach chemicals ((bisphenol) into baby formula, bisphenol is linked to various cancers in later life. This evidence is so strong that on the 22/4/08 the Canadian government banned the importation and sales of plastic baby bottles. Other governments consider similar bans. It is difficult to understand that it would take years after the introduction of plastic baby bottles to make such a discovery!!

How long will it take before plastic water tanks are declared unsafe to store drinking water ??

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

Update 6/6/08: There is now hard scientific evidence that water stored in plastic tanks may present a health risk indeed.For more information mail a self adressed envelope to PO. Box 16, Cannon Hill, 4170 requesting the free DVD  "Phthalates (plastisisers), effects on the human endocrine system" 

Q: Is it advisable to chlorinate my tank water?

I am aware that some authorities make recommendations to chlorinate tank water.I have some reservations to this for the following reasons. Firstly, accurate calculations and measurements have to be carried out to ensure the correct amount of chlorine is added to the tank. From my point of view, due to the toxicity of chlorine and the danger in handling it, plus the potential of overdosing, this is no task for the handyman. Secondly, there are  much better and safer products available (Aqua Safe or UV sterilisation) which are more suitable and safe to handle.

Q: I noticed the inside walls of my plastic tank feels slippery and soapy, is this normal?

What you feel is called a "biofilm", not desirable to have in your water tank. A biofilm is a layer of microorganism contained in a matrix (slime layer), which forms on surfaces in contact with water. Biofilms provide a "safe haven" for organism like listeria, e.coli and legionella, where they can reproduce to levels where contamination of the water becomes unavoidable. The best way to remove this contamination is to get your tank cleaned out and the walls washed down with a water blaster. Chlorination of your tank water will only destroy the top layer of the biofilm and it will regenerate. Unfortunately plastic surfaces are most suitable for biofilms to establish, this is one of the reasons why most containers in hospitals are glass or stainless steel.

Q: If there is scientific evidence that plastic (poly) may in fact contaminate the water, why is there no legislation to prohibit the sale of polytanks?

Governments are notoriously slow to respond (exceptions to the rule: the Canadian government which banned the sale of plastic baby bottles days after a relevant study proved that bisphenol leaches into the formula). The main reason can be found in the lobbying power of some very influential industries.  The best example are cigarettes, the link between smoking and  rather serious and terminal diseases has been established decades ago, but tobacco is still for sale. On the other hand, customers are free to make an informed decision. 

Q: Is it safe to drink untreated rainwater?

With the introduction of plastic tanks, a whole new industry has been created. Refer to your Yellow Pages to find numerous businesses which specialize in the repair of plastic tanks. The UV rating of your tank gives a fair indication of the expected life span. The first manufactured  plastic tanks had an UV rating of 8 or 10, this tank are failing now. More recent fabricated tanks have a UV rating of 16, which is the maximum possible rating.You can extend the life span of your plastic tank by locating it in a shaded position, or the best solution would be under a roofed area.

Q. What about fire resistance of a stainless steel water tanks?

The only tank that is truly fire proof is a concrete tank. Although a bush fire cannot harm the stainless steel besides making it black, prolonged exposure to extreme temperatures will eventually destroy the seal depending on how much water is in the tank. The seal is replaceable. Plastic tanks are legendary to catch fire themselves in such an emergency. Aquaplate, contrary to what some tank manufacturers state, are most sensitive to temperature over 70 degrees. The plastic coating inside the tank will separate and render the tank useless. Zincalume will perform slightly better than aquaplate, up to about 200 degrees when the zincalume coating will melt. 

Q: Is the taste of rainwater jeopardised by a plastic rainwater tank?

A large beverage manufacturing plant in the North of Brisbane intended to market bottled water in the first half of 2005.  A bottling plant was installed and as buffer storage, 4 x 40,000L plastic tanks were used. The first production run of bottled water did not pass the plant's stringent quality assurance test in respect of the taste.  The project was put on hold until a more suitable stainless steel tank could be sourced. 

Q. Can a stainless steel tank be put in-ground?

The tanks are not designed to be fitted inground, and we have no engineering data to state that inground mounting is permissible.

A very sensible question. Prior to answering this question, we would like to draw attention to other 20- 25 year warranties;

To come back to the original question, our warranty is only viable for as long as Stainless Rainwater Tanks is in business. Although, we are currently negotiating with a major insurance company to carry the risk of our tanks for 40 years. If this negotiation would be successful, it would be a unique first in the industry. Currently, our warranty is based in the untarnished reputation of 304 stainless steel. Whenever your kitchen sink will rust out, so will our stainless steel tanks.

Q. My Aquaplate Tank developed a leak,can I put a tank liner to overcome this problem?

At first it appears to be an elegant solution to fit a plastic liner into a steel tank.  A more detailed examination reveals a different story.  The purchase and fitting of a liner into a 20,000 L (5,000 Gal) tank may cost up to $1000.00.  To invest this amount of money in a steel tank is not cost effective but worse is to come, the plastic liner will NOT  prevent your steel tank from rusting away internally.  The outcome is, the steel tank will burst open when the rusting progress to the stage that it can no longer support the liner. Sometimes with catastrophic consequences. 

Of course, a plastic liner in a cracked and leaking concrete tank may extend the life of the tank for many years.

Q. Can a hailstorm damage my Stainless Steel Tank?

Heavy hail will dent the roof of the tank, comparable to a hail's damage to a car.  The tank currogation will withstand hail with very minor damage. The usual house and contents insurance should cover such damage.  Our experience shows that insurance companies would generally pay for a new tank.  Of course, the "old, damaged tank" is still perfect for use compared to a hail-damaged car. It may not look the way you like it but it still drives perfectly well. So you may end up with 2 tanks. The alternative would be to call a scrap merchant to collect the tank. Currently (2006) you can expect to collect between $500 and $600 for a 5000 gal . stainless steel tank.

Q. How much water can I harvest from my roof during the year?

A very good question.  The answer cannot be straightforward and some assumptions have to be made to get an indicative figure.  My calculations are on the conservative side, due to different circumstances and location.  Statistics indicate that the Greater Brisbane area has an average annual rainfall of about 1150mm.  I work with 1000mm due to the fact that the higher figure was calculated in 2004 and average rainfall appears to decrease in the last couple of years.  Lets assume that the catchment area (roof) is 300sq meters.  Again, this estimate is on the lower side of the average roof area. 

1000mm x 300 sq m = 300,000L/year

Certainly, a staggering figure. The average household in Brisbane uses about 280,000L/year. Theoretically, if you could catch all the rain during the year, your household would be self-sufficient.  Practically, only under  ideal conditions you will be able to harvest all the rain as it falls.  In the worst case scenario, up to 50% of this water is lost due to overflowing gutters (not cleaned) and clogged up inlet strainers in the tank.  Well maintained (clean) gutters and inlet strainers in your tanks will ensure that only a fraction of this precious resource is lost.    

Q. What type of base is suitable for a Stainless Steel tank?

Our recommendation is always to use a concrete base, for the reason that stainless steel on a concrete base will last as long as your house if not longer. Regardless, we estimate that approximately half of our tanks are placed on crusher dust or sand.  This is acceptable, but care has to be taken that the crusher dust cannot be undermined by water or vermins. A typical example is that the overflow water is allowed to run down on the outside of the tank (in this context it has to be noted that overflow water on the outside of an aquaplate tank will immediately void the Bluescope warrantly). This is no issue with a Stainless Steel tank, but if this water undermines (washes away) the base of the tank and would consequently damage the tank, any warranty claim will be denied.  For this reason, it is appropriate to enclose the crusher dust with sleepers, bricks, besser blocks or similar. It is always a good practice to pipe the overflow away from the tank. Pavers can also be used as a tank base, and provide a good economical base for water tanks.  Note that a crusher dust base is not suitable for our super slim and standard slim series of tanks.