Wednesday, 1 February 2023 Knowledge Articles
Underground Stormwater Tanks – Which is best, concrete or plastic?
We're frequently asked which material is best. To us, plastic stormwater tanks have clear advantages.
More homeowners are installing their stormwater tanks underground to save space and improve the aesthetics of their properties. In the industrial sector, too, we're seeing a trend toward underground tanks.
However, while there is no doubt about their increasing popularity in all sectors, things are a little less clear-cut regarding the best material for underground stormwater tanks; is it plastic or concrete? Architects, engineers, builders and homeowners frequently ask us this question and, as you'll read, we believe plastic is the correct answer in more ways than one.
Traditional thinking might lead you to conclude that concrete is strong and durable, making it the ideal material for underground tanks. Unfortunately, that's not always the case; all the evidence we need is in our backyard. It became apparent during the Christchurch and Kaikoura earthquakes that rigid structures like concrete tanks didn't perform well during the tremors. Their lack of flexibility counted against them, and that's why Promax replaced many badly cracked concrete water tanks after the earthquakes.
On the other hand, we have had no recorded failures of our plastic tanks after these seismic events.
This was no great surprise to us. We design our polyethylene water tanks to be remarkably tough while retaining enough flexibility to withstand significant ground movement. This is just one of the many benefits of Promax plastic water tanks, including our corrugated underground models. Geotechnical experts design and engineer our underground tanks, which are then Finite Element Analysis tested (FEA). Promax corrugated underground tanks are light and easy to install, which reduces handling costs. In addition, they can withstand ground and water pressure at depth, meaning you can trust them in a wide range of settings, e.g., under driveways, footpaths, car parks, and forecourts.
Here are a few other things that make our plastic underground stormwater tanks a better investment:
- Fast Delivery – Promax holds stock of all standard sizes to improve delivery times.
- Maintenance – 600 mm diameter utility hole and lid for easy inspection.
- Durability – One-piece rotational moulding for most sizes provides extra durability.
- Adaptability – It's much easier to add fittings to plastic tanks.
- Affordability – Plastic tanks are very cost-effective compared to concrete
To keep things simple, we standardise Promax Tanks in incremental capacities from 1,000 litres up to 30, 000 litres which suit virtually all applications. Furthermore, depending on invert levels and site space availability, they're available in standard diameters of 750mm, 900mm, 1200mm, and 1900mm.
In summary, our underground stormwater tanks come in the size you need, for the setting you want, and with the strength you require. That's why we firmly believe that plastic is the best material for your underground stormwater tank.
Contact us for further information and advice to help you make the right decision.