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  Underground Fiberglass Tanks

Fextex offers horizontal underground fiberglass tanks manufactured by Xerxes / ZCL. are 100% watertight when installed to the manufacturers installation instructions. This minimizes your pumping costs- inflow and infiltration are eliminated, allowing the re-circulation tank to pump effluent from inlet assembly and filter return. Fiberglass tanks by nature are anti-corrosive, eliminating the need for internal and external liners concrete, and steel tanks require.

Underground Fiberglass Tank Features


  • Underground fiberglass tanks' water tight connections are ensured by fiber-glassing the PVC inlet and outlet fittings.

  • Underground fiberglass tanks offer flexible design options including configuration for riser openings with internal flanges  ​(used to hang pump vaults for turbine pump applications), pump platforms (used for centrifugal pump applications), pump quick disconnects, slide rails, anti vortex plates, baffle walls, smoothing inlets & bottom sumps. 

  • Underground fiberglass tanks are light & easy to install while remaining strong to withstand an H-20 traffic load.

  • Standard underground fiberglass tanks can be buried up to seven feet deep. If your application calls for a deeper bury we can provide a MTO (made to order) tank with thicker walls. Wall thickness of tank will be determined by burial depth.

Underground fiberglass Tanks
Underground Fiberglass Tanks


  • Underground fiberglass tank system evaluation, ensuring the provided products match the system design

  • Training guides, and unlimited personal assistance to the contractor to ensure proper installation

  • Assistance with obtaining back fill approval, and letter from tank manufacturer

  • Underground fiberglass tank anti buoyancy calculations

  • Underground fiberglass tank dipstick calibration charts (indicates liquid level per tank height) Helps set float heights, calculate liquid capacity of tank and dosing volumes

  • Fextex provides design tools including drawing layouts, material specifications & installation manuals

  • Fextex can generate project specific CAD drawings that can be incorporated into the construction plan set.


Underground Fiberglass Tank Services
25,000 gallon fiberglass wastewater tank
Fiberglass Wastewater Tanks

Fiberglass wastewater tanks are used as holding tanks, STEP tanks, recirculation tanks or dosing tanks.  Multi- purposing your fiberglass wastewater tank can save space, installation time and overall cost. more...

10,000 gallon Fiberglass Fire Protection Tank
Fiberglass Fire Protection Tanks

Fiberglass fire protection tanks are used for emergency storage. The tanks are often equipped with bottome sumps for full drainout capabilities, or in tandem with a vertical  fiberglass wetwell. more...

20,000 gallon fiberglass tank
Fiberglass Potable Water Tanks

Fiberglass potable water tanks are stamped NSF 61, and come standard with a 30 year warranty. Potable water tanks are sometimes used for a dual purpose, such as storing water for emergency fire protection. more...

fiberglass wetwell
Fiberglass Wetwells

Fiberglass wetwells are an easy to install, long term, watertight solution for storing potable/non potable water or wastewater.

They come in diameters up to 12' and can be buried up to 50'. more...

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