Different Types of Water Tanks

Steel Tanks

Steel is a common material used in manufacturing water tanks. Although steel rainwater tanks are tough, they are also prone to corrosion. Steel tanks are mostly coated with rust resistant coatings such as zincalume.

Brand new steel tanks usually need to be flushed before they can be used. This is because these tanks mat leak excess concentration of zinc, which may not be deadly, but could affect the taste of stored rainwater.

The most common material used in manufacturing steel tanks is galvanised steel, which is basically applying zinc to steel. These steel tanks are commonly joined using a hot iron to combine lead and tin on the joint of the steel. Like other types of steel, galvanised steel is not resistant to corrosion so manufacturers also need to apply rust-resistant coatings to these tanks.

Steel tanks fabricated for water storage do not have corrosion issues like galvanised steel tanks. However, they cost more than plastic coated tanks and galvanised steel tanks.

Steel normally have a warranty period of about 20 years, however, the manufactured product or steel water tanks only have a 10-year warranty on a pro-rata basis. Should you choose this type of tank, it is very important that you read the warranty guidelines carefully.

Concrete Tanks

Another popular material used for manufacturing tanks is concrete. Concrete tanks are usually very heavy, difficult to transfer and install. Normally, an 18,000 litres concrete tank would weigh about 8.81849 tons.

Large concrete tanks are often installed underground, while smaller tanks can be installed above ground. Small tanks are commonly delivered complete, while medium and large tanks are poured on site.

Concrete tanks are delivered in 3 pieces and the openings are covered by rubber or synthetic sealing ring. A sealant is applied to the inside part of the tanks at the join. This stops the water from leaking out.

New concrete tanks may affect the taste of stored water and may leak lime, which increases the pH level of stored water. Therefore, it is advisable to flush these tanks before using them.

Common issues with concrete tanks include cracking and leaking. What repairmen do is to drain the tanks completely or to the portion of the crack and use a sealant to repair the damage. Sometimes, a plastic liner needs to be used in order to repair extensive damages to the tank. Such cases can be a bit expensive.

Fibreglass Tanks

Fibreglass tanks are manufactured using a food-grade coating on their interior surface. It usually takes time for this coating to be cured, so production also takes a bit of time. But the wait is worth it.

One good feature of fibreglass is that it’s very rigid, which means that the wall of the tank can be thin to manage water pressure. Fibreglass tanks are often manufactured with resin mixed with a hardener. Along with the glass fibres, the catalyst or hardener is sprayed on to a mould by an operator. Doing this makes these tanks sturdier. However, this process is dependent on individual skill, which results in a variation from tank to tank.

Like concrete tanks, fibreglass tanks are also prone to cracking and leaking. Since fibreglass allows light to pass through it, algal growth is also possible. However, to prevent this from happening, manufacturers use a black covering inside these tanks or they are often painted on the outside. Some of these tanks are designed with sufficient pigment to address this issue.

Plastic Tanks

Plastic tanks are the most popular types of the water tank in New Zealand. Mostly, these tanks are many of food-grade polyethylene plastic to comply with AS/NZS4020. Polyethylene is not prone to corrosion, which means longer life for plastic tanks. This also means that plastic tanks are lightweight, easy to transport and easy to install.

Plastic tanks are also inexpensive compared to other tanks. There’s no need for heavy equipment to install them. They are manufactured and delivered in one piece, so you don’t need sealants during installation.

Polyethylene is also a tough material, which allows people to bury it at depth or install them above ground. This is especially applicable to corrugated water tanks. These tanks are also manufactured to withstand earthquakes, which tend to happen often in New Zealand.

Plastic also prevents light from passing through, which inhibits the growth of algae; a problem that fibreglass often encounters.

As with all types of water tanks and rainwater tanks, these tanks also need to be flushed after installation to make sure there are no dirt and taste distinctions.

And lastly, polyethylene tanks can be recycled at the end of their service life. You can use this type of water tank for storing water for doing your laundry, washing your car, for your garden, and a whole lot of applications.