How to Install an Underground Water Tank

Underground Water Tank

Underground tanks are excellent water storage solutions for rainwater harvesting or areas that do not receive an adequate piped supply. Their location is ideal as they do not take up much space because they are hidden underground.

You can install an underground water tank yourself or have it done by a professional. The best underground tanks are concrete, steel, fiberglass, or plastic materials. Depending on your budget and the size of the tank, one can choose the type they prefer. Concrete tanks, however, are more durable and easy to install and maintain.

The water stored in concrete underground tanks does not freeze during cold weather and will remain warm from the earth around it. Similarly, in hot months, the water is cool enough for relaxing everyday use. The tanks do not get easily damaged as they are not exposed to the environment or easily accessed by animals.

Benefits and uses of Underground Water Tanks

Underground tanks are popular in Australia. They are ideal for emergencies and provide all-year water collection and storm or rainwater storage. Besides home water storage, there are many other uses for underground water tanks. They include;

  • They act as a water reservoir for irrigating gardens.
  • They create a water filtration system for drinking water.
  • Storage of water for use by fire departments to fight forest fires.
  • Provide water for animals and livestock on a farm.

Advantages of Underground Water Tanks

  • They save money as one can store rain/stormwater and avoid paying high monthly bills for piped city water.
  • They require little space as they are hidden below the ground. They will not take up your yard or garden space.
  • They are not visible and will not tamper with the environment or landscaping.
  • Water stored underground is safe to use as it’s not easily accessible for contamination.

What to expect during An Underground Water Tank installation

Before installing an underground water tank, besides using the right tools and equipment, consider a few other things.

  • Consent for the installation works. Although the council will not ask for permits for small underground water tank installation, ensure to confirm with your local council.
  • The site of the tank. Choose the best place for your tank based on water runoff if the tank is for rainwater storage. Ensure the ground or soil is easy to excavate. If not, provide the necessary equipment and resources.
  • Size of the tank. Choose a size that will meet all your household needs.
  • Plumbing/Piping. Ensure all the necessary water piping and plumbing are laid down before installing the underground tank.
  • Overflow system. Protection against overflow is essential. It protects the tank from insects and dirt getting into the water or dirty water from the ground flowing back in.

Underground Water Tank Installation process

  1. Excavate the ground to the desired depth, length, and width. Leave enough room at the top to cover the tank.
  2. Prepare the bottom where the tank will rest. Ensure the soil is compact and well levelled. Some builders install a concrete base.
  3. Lower the tank into the centre carefully until it is well balanced.
  4. Fix all the necessary connectors and fixtures for the plumbing or piping works and add the required risers.
  5. Fill all the empty spaces around the tank well with the recommended soil and gravel. Ensure to cover the top of the tank to avoid water seeping in.


Once you set up your underground tank, have regular maintenance checks conducted. The inspections ensure the installation was done correctly and the plumbing system is working well. If the water is for household use, check the quality regularly for safe drinking.

Read Also:
Above Ground vs Underground Water Tanks
A Guide to Underground Concrete Tanks

About the Author: Varun Rana

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