Are designed specifically for underground use based on their rotationally moulded design and application. These tanks are often required for property owners who need water storage but cannot have a tank visible on the surface, or to preserve land use and space. The underground installation also protects the tank and contents from the effects of sunlight, which can be damage to the tank resin and microbiological growth.

These tanks are commonly constructed of high-quality, virgin polyethylene that is regulation-approved for potable (i.e. drinkable) water. Underground tanks work with a pump and pipe system to transport water in the storage tank to application areas. Underground water storage tanks are installed at a depth to protect them from freezing in areas that experience such temperatures..

Benefits of an underground tank versus an above ground tank:

  1. Microorganism Prevention — Underground storage tanks are out of direct sunlight that can warm the water and stimulate the growth of algae and other microbial growth.
  2. Consistent Water Quality — The temperature of water from the underground tank may hold at 42 – 48 °F (6 – 8 °C) year round. Algae and microorganisms cannot form at this temperature in darkness and temperature, ensuring consistent water quality.
  3. Land Usage — Important above ground land space is saved and can be utilized for other purposes; a very important point in areas where space is limited. As long as it is clearly marked, an underground storage tank less likely to be damaged.