Underground water storage tanks are used for storing rainwater underground. They are manufactured in a way that it can be buried underground easily and these tanks cannot be used above ground. It does not store only rain water but a high-quality plastic water storage tank can store potable drinking water as well.

Tank flotation is a serious issue and it can damage the tank or other attachments of the tank. In order to protect the tank from flotation, you need to follow the procedures and guidelines for tank installation. When we throw a half-filled bottle into the water, it floats because the air within the bottle exerts an upward force. This process is known as buoyancy. The same way, underground water tanks are huge in size and contain a large volume of liquid, the force is extremely strong and can cause buoyancy leading to a damage to the tank.

While installing a tank, the two important factors that should be taken care of includes weather conditions and groundwater pattern. Many areas tend to collect water and backfill material which is not a favorable situation while installing an underground water storage tank. Weather can change anytime, therefore this situation should be accounted for while installing the tank. There are a number of elements to prevent an underground water storage tank from floating. These include the following:

Bury the underground water storage tanks deeper as the weight of the backfill will exert downward pressure which will counteract the effects of buoyancy. The full depth of cover should be placed to protect the tank from floating.

An alternative is deadman anchors, in cases, where the burial depth cannot be increased. They are made of reinforced concrete which provides additional stability and prevents flotation. In some cases, full concrete hold down pads are required to be placed below the tank.

In many cases, when placing water during the construction phase, ballast for the tank is provided which prevents flotation. Also pumping of the groundwater during construction is recommended until the tank is completely backfilled.

Use thick paving slabs above the tank when placing the same as it will create more downward pressure and keep the underground storage tank in place.

One single issue does not cause flotation but a sequence of missteps is the reason behind the occurrence. These precautions are important and should be followed to keep the tank in place.  It should start right from the beginning at the time of planning and construction.

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