Today’s Composite Elevated Storage Tanks - Presented at the 2002 AWWA Conference & Exposition - New Orleans, LA

Oct 28, 2026

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Composite elevated water storage tanks, using a welded steel tank atop a reinforced concrete pedestal, have grown in popularity over the last two decades. Despite this adoption, widely recognized construction guidance lagged behind, leaving owners, engineers, and designers without consistent standards. This paper summarizes the development of composite tanks, reviews today’s design concepts, outlines the status of the AWWA D170 standards process, compares composite tanks with AWWA D100, and explains how to properly specify a composite elevated tank.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages16

Reading Time40 min

AccessFree to download

What is a Composite Elevated Tank?

Basic Configurations and Style Comparison

Style A: Domed Concrete Floor with Liner

Style B: Suspended Steel Bottom

Style C: Concrete Slab with Liner

History

Standards Development Activities

Today’s Composite Elevated Storage Tanks Presented at the 2002 AWWA Conference & Exposition-New Orleans, LA Stephen W. Meier, P.E., S.E. Vice President of Engineering and Technology Tank Industry Consultants Indianapolis, IN Abstract: Over the last two decades, composite tanks for water storage—tanks with a steel tank storage container atop a reinforced concrete pedestal—have gained popularity. The challenge for tank owners, engineers, and designers has been that no widely recognized standards were in place to provide guidance for the construction of these types of tanks. AWWA Standard Committee D170 is working to fill that those gaps and provide a comprehensive standard that will supply tank owners and specifiers with the tools needed to design, specify, build, and maintain these structures. It will also aid the tank owner in better determining the type—steel, concrete, composite—tank that will best serve their water system needs now and in the years to come. This paper reviews the development of the composite tank and includes a state-of-the-art look at what concepts are being built today, the status of the standards process, how composite tanks differ from the AWWA D100 tanks, and how to properly specify a composite elevated tank. Mr. Meier chairs the AWWA Steel Elevated Tanks, Standpipes & Reservoirs Committee and has been a member of the AWWA Composite Tank standard committee since its inception. In addition, he is a member of the ACI 371R Committee; the American Concrete Institute recommended practice for the design of the pedestal. What is a Composite Elevated Tank? A composite elevated water tank is comprised of a welded steel tank for watertight containment, a single pedestal concrete support structure, a foundation, and accessories. These tanks are also sometimes referred to as “concrete pedestal elevated tanks.” The steel tank provides a proven, watertight container derived from the AWWA D100 Standard for welded steel tanks which has demonstrated superior performance through decades of use by the water industry. The reinforced concrete support column provides a cost effective, structurally robust pedestal with minimal maintenance. Today’s Composite Elevated Storage Tanks Page 1 S.W. Meier The basic configurations ofthe composite elevated storage tanks built in the US and Canada over the last 25 years is shown in Figure 1. | Figure 1-Common Composite Tank | | | | --- | --- | --- | |

Style A-Domed Concrete Floor with Liner |
Style BSuspended Steel |
Style C-Concrete Slab with Liner | The most common composite tank is the domed concrete floor with a carbon steel liner (Style A) . The advantages and disadvantages of each style are shown in Table A. Table A – Advantages and Disadvantages of the Styles | Style | Advantages | Disadvantages | | --- | --- | --- | | A-Dome | • Balance of forces at tank-topedestal intersection
• Scalable to large capacity tanks
• Reduced dead storage (i.e. water quality) | • Special formwork
• Intersection with steel tank more complex
• Liner fitting/grouting dome shape
• Underside of liner inaccessible for coating similar to a ground storage tank
• Additions or modifications to tank bottom are difficult | | B – Suspended Bottom | • Bottom is accessible for coatingsand addition or modification | • Tolerances at top of pedestal critical for skirt support
• Skirt-to-cone intersection design
• More dead storage
• Condensation on bottom may require a condensate ceiling for interior uses | | C-Slab | • Simple forming
• Liner is not formed ( similar to flat bottom tank on slab) | • Limited to smaller capacity tanks
• Bending tension stresses cause cracking in lower face of slab
• Bending moments in top of pedestal
• Underside of liner inaccessible for coating similar to a ground storage tank
• Additions or modifications to tank bottom are difficult | Today’s Composite Elevated Storage Tanks Page 2 S.W.

FAQs

What problem does the AWWA D170 committee aim to solve for composite elevated tanks?

It addresses the lack of widely recognized standards that would guide the construction and specification of composite elevated water storage tanks, enabling owners and specifiers to design, build, and maintain them consistently.

What is a composite elevated water tank made of?

It consists of a welded steel tank for watertight containment, a single pedestal reinforced-concrete support structure, a foundation, and accessories.

How do composite elevated tanks differ from AWWA D100 welded steel tanks?

Composite elevated tanks combine an AWWA-derived welded steel tank with a concrete pedestal support, and the paper discusses how their specification requirements differ from AWWA D100 tanks.

Oct 28, 2026

Upload by Mabel