Category Archives: Water Tanks

Have You Experienced Flooding? You May Need A Detention Tank

If you are building a new home, there may be several requirements that you’ll need to meet. One of these requirements might be stormwater management, which will require the use of a detention tank. If you are experiencing flooding, a detention tank may also be your answer.

What are detention tanks?
Detention tanks are large tanks that are normally installed below the surface and used to suppress the effects of heavy rainfall, or stormwater. They work by temporarily storing the rainwater runoff during rainfall and slowly release the water through a small diameter orifice into the public storm water system. This reduces the peak flows of stormwater and reduced the chance of flooding due to an overloaded stormwater system.

Detention tanks are usually required in areas where storm water flooding risks are high. This is especially true in many areas in Auckland, with the current increase in population and housing. Generally speaking, if you are adding roof space by extending or building a new home in areas where stormwater systems have not been renewed, you will most likely require a detention tank.

Detention tanks can also be useful for managing stormwater onsite. This is most common used in combination with soak holes. This systems gives the ground enough time to soak excess water which prevents any surface or ground related flooding.

How big does my detention tank need to be?
In Auckland, a rule is based on several conditions such as the “storm of the 100 years” principle, which would be to allow for 100 liters per 1 square metre of roof surface area. Depending on detention requirement, the outlet orifice can range between 10mm-40mm. Some further information can be found regarding size of detention tank from Auckland Council here.

We at Rotational Plastics can help you get the detention tank you need for your home. See our large range of plastic detention tanks or call us on 0800 768 284 today!

If you are looking for a Drainlayer to install any of our tanks, please don’t hesitate to call Drainage NZ for a free quote.

Are You Flooding? Get A Detention Tank!

If you are living in an area that is constantly being developed or re-developed, chances are you deal with street floods whenever there’s a storm or heavy rainfall. The reason for this is that urban development increases “hard surface” which doesn’t absorb water, unlike soil and grass. Examples of hard surfaces are concrete paths, roofs and paved areas.

Intense rainfall dumps large amounts of water on your property. And since stormwater is no longer being absorbed into the land, there is increased run-off into local stormwater systems. As more dwellings are built, the public infrastructure becomes considerably undersized.

A good solution to ease the pressure on existing infrastructure is installing detention tanks. In fact, this is now a mandatory requirement for new homes as well as extensions. Having a detention tank plumbed into your existing drainage system is also encouraged as it makes stormwater run-off more manageable.

What is a detention tank?

A detention tank stores water collected from your hard surfaces during a rainfall event, then releases the water into the public drains at a slow, controlled rate. The slow release of the stormwater reduces peak stormwater flows and, in turn, reduces the impact on stormwater systems as well as the chance of flooding.

Detention tanks are different from rainwater retention tanks. A retention tank is a normal water tank which simply harvests rainwater and “retains” it for domestic use. Most retention tanks can only hold so much water. In case of intense rainfall, they can quickly fill up and the water overflows into the local drains in an uncontrolled manner.

On the other hand, a detention tank is intended to remain empty to make space for stormwater runoff during periods of rainfall.

It should also be noted that stormwater is different from rainwater.

Rainwater refers to rain that falls on roofs, while stormwater refers to rain that falls on hardstand surfaces other than roofs. The distinction lies in the quality of the water. Research has proven that although rainwater harvested from a roof may contain dust or debris, the debris is likely to be organic and the quality of the water makes it excellent for use in the household. Meanwhile, stormwater may have potential contaminants such as oil drops, pet droppings and rubbish.

Detention tanks may be installed above or underground.

Detention tank solutions

A detention tank is designed to empty the required amount of water at the required rate.

How big your detention tank should be depends on the specifications required by your local council. The council will also specify the size of the orifice and the flow rate of water from your detention tank. In most cases, a certain percentage of your roof or ground area will be specified for use in harvesting stormwater.

Aside from the specified size and capacity, these are the things to consider when selecting a detention tank for your property:

  • Space and budget considerations
  • Aesthetics
  • Ease of installation
  • Maintenance

If you need help choosing the right type of detention tank, contact us on 0800 768 284 and we’ll talk you through the specification and building process.

What Are Our Most Popular Products?

When you sell such a wide variety of products like we do at Rotational Plastics, naturally the question comes up. What is the most popular product in our range? We had a look at our statistics to see the answer.

It turns out that tanks are the most popular category of product on our website. People love our plastic tanks, whether for retention, storage or even spray water tanks. But why are tanks so popular?

Many people are looking to move off the grid, and water is one of the main utilities which you don’t have control over unless you collect your own. With a water tank, you can collect and store your own water. This is also an excellent option in more rural areas where mains water supply is not available.

What does our range of tanks include?

Above ground tanks – Above ground tanks are increasingly common across New Zealand because they are a cost effective way to collect and store water. The advantage of these tanks are that installation and maintenance is both cheap and easy, since the tank is easy to place and get to. There is no excavation needed. When maintenance is needed, which involves emptying and cleaning the inside, this is much easier with an above ground tank – simply hose down the inside and tilt the tank to drain the water.

Below ground/underground tanks – These tanks are installed either partially or completely under the soil, and are another popular option. However, they are a more permanent solution, as they require excavation to install them. The benefit is that they don’t take up any space above ground, so you still have a backyard to enjoy. They are most often installed during the building process of the home, minimising installation costs and inconvenience once the home is built. Underground tanks need to be reinforced in order to handle a long life underground.

Mobile home water tanks – These are the perfect solution if you need to storage water in your mobile home. Also good for boats, these plastic tanks won’t corrode and will ensure that your water stays clean and protected. These come in a range of shapes and sizes to suit a wide range of applications.

Spray water tanks – These are tanks with pressure washing systems. They come in a range of sizes and shapes and can be used for many applications.

Check out our website now for a wide range of plastic water tanks in all shapes and sizes!

All About Detention tanks

You maybe have been browsing our website and no doubt came across our detention tank range. There are tanks in all shapes and sizes. But what are these tanks actually for?

Detention tanks, which are sometimes called retention tanks (though this is incorrect), are generally used when storm water system in not adequate enough to deal with the job of extracting water. The detention tanks works to slow down the rain that comes off your roofs and goes into the stormwater system, to prevent overflowing. This is generally an issue in older areas where a lot of new houses are being built and a lot of strain is being put on the stormwater system. Where this is an issue, councils often require the use of detention tanks.

What happens if you have a retention tank is instead of the water flow straight into the stormwater, it comes off the roof and other areas and into the detention tank, then drains slowing through the orifice outlet into the stormwater system. The tank and orifice will be specified to drain at a certain rate, depending on what the stormwater can handle. This can take hours depending on the flow rate. The area your building is in will have specific requirements for this.

Detention tanks can be stand alone units, but often times there are combined with a retention tank. The retention tank stores water for when you need it, in contrast to the detention tank. So how this works will be if you use a 3000 litre tank, the bottom 2000 litres will be used to store your water, and the top 1000 litres for detention.

So what do you need to look for when buying a detention tank? The first thing you’ll need to look at are the council requirements in your area for water flow. You need a tank that will meet these requirements, which will determine the size your orifice you need to select. If you are going to going to be getting a combination retention tank, then you also need to take into account how much water you need for storage. You also have the choice of above ground or below ground.

We have a wide range of detention tanks on our website in all kinds of configurations, sizes and shapes. Have a look through our range and contact us if you need assistance selecting a tank for your home!