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Watco Permatank Outside
BUILT THE WATCO WAY

STI PERMATANK®

A double-wall jacketed underground storage tank featuring an inner 
steel tank and corrosion-resistant exterior coating, engineered for
strength and longevity.

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WATCO TANKS

NextGen Performance and Proven Reliability

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Key Technical Advantages

Design Efficiency

Reduces length to maximize storage without sacrificing real estate, designed shorter than fiberglass tanks of the same capacity, reducing installation costs and increasing layout flexibility
Durability

14-gauge steel replaces previous standoff material, creating a tight interstitial space. Braced double bulkheads provide dual sealed protection between contained liquids and are reinforced with vertical bracing for superior structural integrity
Fuel Compatibility

Steel construction ensures compatibility with all hydrocarbons, ethanol, and biodiesel blends, and can be lined for DEF and JetA/AV Gas applications
Ease of Install

Anchoring is not required, optional Watco-manufactured deadman and anchoring packages are available to maximize ease and installer convenience
Sustainability

Steel construction allows for recycling, supporting environmental sustainability
Built-in Safety

Features a durable non-slip grip with OSHA-level strength for superior safety during installation
Capacity Range

Available in double-wall construction with capacities up to 40,000 gallons, providing scalable solutions for diverse storage needs
Watco Tanks Strength in Layers

STI Permatank® New and Improved Steel Jacket Design

Our latest Permatank is enhanced with 14-gauge steel, replacing the previous standoff material, creating a tight interstitial space for long-term performance.

Watco Steel Seperator Material Annotated

Permatank® Design Specifications

Standard Dimensions and Tank Capacities

Diameter Capacity Length +/- 2" Weight +/- 5%
96" 8,000 gal 21'-9" 11,000 lbs
96" 10,000 gal 27'-2" 13,000 lbs
96" 12,000 gal 32'-7" 15,000 lbs
96" 15,000 gal 40'-8" 18,000 lbs
96" 20,000 gal 54'-5" 27,000 lbs
120" 7,000 gal 17'-4" 12,000 lbs
120" 10,000 gal 20'-10" 13,000 lbs
120" 12,000 gal 26'-0" 16,000 lbs
120" 15,000 gal 30'-8" 18,000 lbs
120" 24,000 gal 41'-8" 27,000 lbs
120" 26,000 gal 45'-2" 29,000 lbs
120" 30,000 gal 52'-1" 33,000 lbs
120" 32,000 gal 55'-7" 35,000 lbs
126" 30,000 gal 46'-9" 34,000 lbs
126" 32,000 gal 49'-11" 34,000 lbs
126" 34,000 gal 53'-0" 36,000 lbs
138" 36,000 gal 56'-7" 37,000 lbs
138" 35,000 gal 45'-6" 35,000 lbs
138" 38,000 gal 48'-5" 36,000 lbs
138" 40,000 gal 51'-0" 39,000 lbs
PERMATANK®

Installation Ease

  • Cost saving backfill material options such as pea gravel, earthen dirt, or clean-washed crushed stone
  • Designed shorter than fiberglass tanks of the same capacity, reducing the cost of installation and increasing site layout flexibility
  • No anchoring required, optional Watco deadman system available to ensure safe loading and unloading of materials
  • Features a durable non-slip OSHA-level grip strength for superior safety
  • Reliable delivery scheduling with coordinated support
  • All tanks are proven tight throughout installation via third-party certification by interstitial vacuum test
STI Permatank Underground Install

Proven Quality Through Independent Oversight


Each Permatank® is certified to meet UL 58, UL 1746, and ULC‐S603.1 standards for steel underground tanks. Every Watco tank undergoes independent third-party inspections by UL and STI, including eight unannounced audits annually. All tanks are backed by STICO Mutual’s 30-year limited warranty.

Since the inception of the inspection program over 25 years ago, Watco has maintained a flawless record — one of only three STI-certified manufacturers to do so.
STI Permatank
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Protect The Environment - Buy Recyclable Steel Tanks
Compatible with a wide range of fuels and chemicals, including biodiesel and ethanol

Permatank® Guideline Specification

 
General
  1. Provide Permatank® double‐wall jacketed steel‐fiberglass underground storage tanks.

Labeling
  1. Tanks shall bear the Steel Tank Institute Permatank® label.
  2. Underground tanks shall bear the appropriate Listing label.

Manufacturer
  1. Manufacturer shall be a licensed member company of the Steel Tank Institute and subject to Steel Tank Institute’s Quality Assurance program.
Product Description
  1. Tanks shall be manufactured per Steel Tank Institute Specification for Permatank®.
  2. Tanks shall be manufactured and listed following Underwriters Laboratories UL 58, Steel
    Underground Storage Tanks for Flammable and Combustible Liquids and UL 1746, External Corrosion
    Protection Systems for Steel Underground Storage Tanks or ULC‐S603.1, Standard for Corrosion Protection
    for Steel Underground Tanks for Flammable and Combustible Liquids.
  3. All tanks shall provide testable secondary containment and access for interstitial leak detection monitoring.

Trusted Watco Tanks Affiliates

Watco Tank Manufacturing Shot

U.S. Leader in UL & STI-Certified Solutions

Every Watco Tank undergoes independent inspections by UL and STI, with eight unannounced audits each year. Since the program's inception over 25 years ago, Watco has upheld a perfect inspection record, a standard achieved by only three STI-certified manufacturers nationwide.

Download the brochure and connect with a Watco expert.

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