AWWA D102: The Rulebook for Coating Steel Water Tanks

If you own, design or maintain steel water tanks, AWWA D102 is the document the work hangs from. It is the American Water Works Association standard for coating steel water storage tanks, and it lets an engineer, a contractor and an inspector work from the same definitions.

Systems, not products

D102 defines coating systems in two families:

• Inside Coating Systems (ICS) for the interior.

• Outside Coating Systems (OCS) for the exterior.

Each system is a generic recipe: surface preparation, number of coats, generic coating types and thickness. A potable ICS is typically an epoxy system over an SSPC-SP 10 blast, with NSF 61 certification required. An OCS might be zinc, epoxy and urethane over SSPC-SP 6, or a fluorourethane finish where long-term color and gloss retention matter.

More than the paint

The standard also covers the steps that decide whether a tank job goes well: blasting and cleanup, ventilation and dehumidification, stripe coating, holiday testing, dry film thickness measurement, cure and disinfection before return to service, and inspection.

Why the edition matters

A specification that cites an ICS or OCS number has already made most of the technical decisions. The job then is to match the right manufacturer's system to that recipe. Systems get renumbered and revised between editions. The 2021 edition, for example, added a section on dissimilar metals, expanded the cathodic protection guidance and removed bolted tanks from its scope.

What to check in your spec

• Cite the current edition, AWWA D102-21, and confirm the system numbers match it.

• Pair the interior system with NSF/ANSI/CAN 61 and disinfection per AWWA C652.

• Include stripe coating, holiday testing and DFT verification as hold points.

• For exteriors that carry a logo or town name, consider a finish with long color retention.

Further reading: Tnemec Technical Bulletin 07-61 R3, AWWA D102-21. Standards: AWWA D102, AWWA C652, NSF/ANSI/CAN 61.

Talk to a consultant. Atlantic Coating Consultants helps owners, engineers and contractors in PA, NJ, DE, MD, DC, WV and OH with specification writing, on-site condition assessment, training, product recommendations and field support. Call 484-644-5303 or email atlantic@tnemec.com.