Water tanks, for most people, are a long term investment, that you want to buy and then forget about – outside of routine maintenance over time to keep them in good condition. And with any investment, it is important to know how long tour water tank will last you.
Some water tank materials and construction methods last longer than others, and this is often indicated by the price of these tanks.
Bladder tanks, frame tanks and tanks constructed from plastic barrels generally last a much shorter time, typically from one to five years. These are helpful if you are just looking for a short term, space friendly or affordable water storage solution but typically do not hold up in the long term like other tanks can.
It is important to remember that any item you use for water storage must be food safe and non biodegradable so that the plastic does not break down into your water supply.
Poly or plastic tanks are made from UV treated, food safe and non biodegradable plastic, and will not break down for some time. Depending on the quality of the materials used to construct these tanks, they should last upward of ten years, and in the best case scenarios will last up to 30 years before the plastic becomes unstable.
However at the end of the service life of a poly tank, the materials are typically not recyclable, and will end up in landfill.
Steel or metal tanks, being made from steel, which is naturally more durable have a longer shelf life than many other varieties of tank materials. Many models of steel water tank have an expected service life of over 30 years if well maintained, and all Southern Cross Water Tanks come with a ten year warranty.
The sheets from steel water tanks are also able to be melted down and repurposed once their service life has come to an end.
The geographical location of your water tank will also effect the life span of the tank. If the water tank is kept near the ocean, the salty air will speed up the corrosion of a steel water tank and potentially of plastic tanks, in coastal areas steel water tanks would need treatment or specific sheeting to aid with protection against the sea air.
If you life in a particularly arid or sunny area, the UV treatments of plastic tanks will not last as long, as the water tank will be exposed to intense UV for longer periods of time, which will lead to an earlier degradation of the plastic.
The location of your tank in terms of where it sits could also effect its lifespan. The type of floor the tank is built on, as well as its relative position to hills and banks will also effect its stability.
What the tank is being used for will also be a determinant factor in the lifespan of a water tank. A water tank with clean fresh water kept in it will typically have a much longer lifespan than that of a tank with salt or chemical water kept in it.
It is also recommended that if a steel water tank is being used to store potable water – or water for drinking and household purposes – that the water tank be fitted with a food grade tank liner both to ensure the long term integrity of the tank, but also to prevent any oxidised zinc or steel from making its way into the water supply due to long term contact with water.
Plastic tanks typically will not need a liner, as the tank itself is already constructed from food grade plastic, but as with steel water tanks, the cleaner the water being used in the tank, the longer the tank will last.
Whilst there is no definitive answer to the question of how long a water tank lasts, typically a steel or poly water tank will last a minimum ten years, with poly tanks often lasting over twenty years, and steel tanks upward of thirty.
Factors that can effect this, however, are geographical location, water quality and the ground the tank is constructed on.