Installation Instructions for Polyethylene Underground Tanks

  • The tank is approved for burial to a depth specified (usually 2 ft.).
  • Do not locate tank under pathway of vehicles or heavy equipment.
  • Keep tank away from large roots and sharp rocks.
  • Do not install tank in areas with high water-table.

Complete Polyethylene Underground Tank Installation

Read through or download and print the complete installation instructions for polyethylene underground tanks.

Installation Procedures


  • Allow enough clearance around the tank to properly place and compact backfill around the tank.
  • Bedding should be well-compacted sand/gravel mixture, 6” minimum in soil terrain and 12” minimum in rock terrain. Shape bedding to suite underside of tank.

Placing the Tank

Prior to placing tank, check for shipping damage. Ensure that the tank is level with respect to inlet and outlet, before starting to backfill.


Install manway cap, and cover open pipe connections prior to backfilling.

Caution: Lid must be kept in place during and after installation to avoid possible manway distortion.

Tank must be buried in pea gravel, surrounding the tank, as per drawing backfill in 12” maximum layers of pea gravel. High water-table (HWT) conditions should be avoided when placing the tank. If HWT conditions exist, contact factory.

Important: Ensure backfill is properly placed around the tank.

During Installation of the Tank

  • Check levelling of tank periodically during backfilling.
  • Backfill and install manway extension (if any) to the surrounding grade level. Refer to drawing.

Pipe Connections

Make solvent weld pipe connections to pre-plumbed tank only when tank is firmly secured and unlikely to shift during remaining backfilling.


These guidelines are set out for proper burial of a polyethylene tank for underground applications, and must always be followed. They are especially important where the soil contains rock or clay. Improper burial may cause damage to the tank and void the warranty.

In case of conditions not covered in this text, or if there are any questions regarding soil or burial method, please contact our factory.

Download PDF Version
Created by

Legal notice