Comparison of Fiberglass Storage Tanks and Other Material Types

Specifying engineers typically have few choices when it comes to materials of construction for water storage tanks. Selecting the proper water tank is an important long-term decision.

Below outlines just a few of the main comparisons between fiberglass, concrete, steel and polyethylene materials.

Fiberglass vs. Concrete

  • Concrete tanks are available in factory precast models and in the case of capacities greater than 4,000 gal., usually formed and constructed in the field, not the preferred factory-controlled manufacturing environment. A one-piece, factory-manufactured fiberglass tank installs in much less time, saving money.
  • Concrete is a very heavy material that limits the ability to easily ship and handle at jobsites while often adding to the expense of installation. Fiberglass tanks are lightweight and easy to install. Thus, they are cost-effective because they do not require heavy equipment to lift the tank and put in place.
  • While concrete is a strong material, the flat-tank top design of a buried concrete tank usually is not rated for traffic load conditions, requiring a design upgrade which adds to the cost. Fiberglass tanks include an H-20 load rating, allowing them to be placed under parking garages and parking lots.
  • Concrete can be subject to aggressive corrosive attacks, often requiring an expensive liner as a solution to protect against this vulnerability to corrosion. Cracking of the concrete generally exposes the steel reinforcement to corrosion, compromising the structure. Fiberglass storage tanks are corrosion resistant, requiring little maintenance.
  • Many designers have concerns about concrete tanks cracking and leaking. Xerxes fiberglass storage tanks are watertight and will provide a reliable water supply for future needs.

Fiberglass vs. Steel

As with concrete, steel has been used to construct aboveground and underground storage tanks for decades. Nonetheless, steel presents certain disadvantages when used to fabricate water storage tanks.

  • One of the significant advantages fiberglass has compared to steel storage tanks is metal can’t match the rust- and corrosion-resistance of composites. With underground storage tanks, corrosion is a major concern. To address corrosion vulnerability, steel tanks are often internally and externally lined or coated, which not only adds to the cost, but also presents long-term maintenance concerns. Fiberglass tank owners can put their mind at ease with a corrosion-resistant storage solution requiring little maintenance.
  • Weight is another benefit to fiberglass tanks when compared to steel tanks. When comparing fiberglass and steel storage tanks, steel can weigh as much as four times that of a fiberglass tank, which generally adds to the installation cost and presents limitations with hard-to-access sites.

Fiberglass vs. Polyethylene

Polyethylene does not have the long history of use in storage tank construction that steel or concrete materials do, but it does provide greater corrosion-resistant properties. Nonetheless, there are other limitations when compared to fiberglass.

  • Underground fiberglass tanks don’t have the many limitations usually placed on poly tanks with regard to common installation conditions such as groundwater table, burial depths and traffic loads.
  • Given structural design considerations, poly tanks are generally limited in capacity. For example, underground tank models usually are limited to much smaller capacities than what is required for typical fire protection tank installations, making it necessary to manifold together many small tanks to get the needed storage capacity. This adds cost and is less desirable than fewer large tanks.