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With new developments and subdivisions popping up like mushrooms throughout the region, there are hundreds, if not thousands, of new householders getting used to the joys of living on tank water.
Aside from the rigours of eking out their supply, whether due to dry weather or water-greedy family members, one thing new residents need to be sure of is the state of their tanks – where they are, how to access them and, most importantly, whether they have been installed and plumbed-in correctly.
This is because, although they are often overlooked or taken for granted, the humble water tank occasionally can and does go wrong and, if it does, it can be in quite a spectacular fashion.
Founder of Warkworth drinking water system specialist Aqua Works Steve Reynolds has seen all sorts of issues in his time, from buried tanks emerging onto the lawn to full plastic tanks splitting in two.
“Overall, installing a water tank is not rocket science. However, you need some knowledge to make it work and avoid unpleasant surprises over time,” he says.
“While plastic tanks are popular and easier to install, they can still have significant problems if not installed correctly, such as split tanks, which we regularly see – not to mention the near-death hazard when 25 tonnes of water decides to let go.”
He says buried tanks might be great for space and aesthetics, especially in a small subdivision, but several factors need to be considered to prevent problems when they’re installed. A tilted or burst water tank can cause a significant safety risk, whether through groundwater contamination or simply by spilling thousands of litres of precious drinking water.
“One important aspect that is often overlooked is the height of the water table, which can be very high and sometimes tidal locally,” Reynolds says.
“If you are burying tanks, adequate drainage around the base is essential to remove surface water.
Sometimes, an extra chamber and submersible pump are needed.”
Failure to take this into account, as well as soil structure and its potential for movement, means your brand-new tank could be popping out of the ground, cracking, splitting, or damaging buried pipework and fittings.
Reynolds says the ground underneath and surrounding a buried tank needs to support a weight of 30 tonnes without moving more than a few millimetres.
“Small issues can be fixed, such as broken pipes or contaminated groundwater, by emptying and cleaning tanks and resealing from the inside and outside,” he says.
“However, if you have a concrete tank popped out of the ground or moving, you have a significant problem. You will need big diggers and possibly cranes to remove the tanks, then prep the site again and re-install.”
He says since a registered plumber/drainlayer has to install all water inlets, overflows and suction pump lines to meet building code, warranty and insurance conditions, it pays to play it safe by partnering with a professional business to design and install any water tanks.
“The storage tank is an integrated part of the rainwater harvesting system, where all components must be perfectly matched to each other to ensure effective operations,” Reynolds says.
“It’s about taking into account all the contributing factors. Choose a company that knows what it’s doing and has experience in your local area.”
Building a house and burying a tank? Questions to consider …
• How high is the water table, and is it tidal?
• Is there adequate drainage around the base to remove surface water?
• Can the ground support a weight of 30 tonnes? Will it move over time by more than a few millimetres?
• What type of tank connections will be used? Will they be flexible, to allow for ground movement?
• Is the tank supported in its hole? What is being used for backfill? Will the side-loading be equal right around the tank?
• Is the tank going to be fully buried? Has at least 100mm been left for the riser to be clear of ground level? Might an extra riser be required?
• Are all the tank penetrations completely watertight, to eliminate groundwater contamination?
• What vegetation will be planted next to the tank? Big trees may need to be mitigated for.
