FDA Food-Grade & Food-Contact Tanks
What "food grade" actually means for a polyethylene tank: FDA 21 CFR 177.1520 for food-contact olefin polymers, NSF/ANSI 61 for drinking-water system components, and the resin and additive considerations that decide whether a tank is safe for potable water and food processing.
"Food grade" is not a marketing word you can stamp on any white tank. For a plastic storage tank it means the resin, colorants, and additives that touch the product are cleared for food contact, and the finished tank is built and cured so nothing leaches into what you store. Two references govern most of this work in the United States.
FDA 21 CFR 177.1520
This is the section of Title 21 of the Code of Federal Regulations that covers olefin polymers — polyethylene and polypropylene among them — for use in articles that contact food. It sets the density and melt-index ranges the base resin must fall within and limits the additives that may be present. When a poly resin is described as "FDA compliant" for food contact, this is almost always the regulation being referenced. The clearance applies to the specific resin and its formulation, so the colorant and any additive package have to be food-contact grade too, not just the base polymer.
NSF/ANSI 61
Where the tank holds potable (drinking) water, the relevant standard is NSF/ANSI 61, which evaluates drinking-water system components for the contaminants they may contribute to the water. A tank certified to NSF/ANSI 61 has been tested so the material does not add anything above the health-based limits. Many jurisdictions and water authorities require NSF/ANSI 61 certification for potable-water storage, so specify it up front if drinking water is the application.
Resin & Additive Considerations
- Natural vs. pigmented resin — food-contact clearances hinge on the exact formulation. A pigment or UV package added for outdoor use has to carry its own food-contact clearance, or the tank is no longer compliant.
- One-piece, seamless construction — rotationally molded poly tanks are formed as a single seamless piece with no interior seams, welds, or joints for product to collect in. That matters for cleanability in food and water service.
- Fittings and gaskets — the tank shell is only part of the picture. Bulkhead fittings, gaskets, and any process connection that touches the product must also be food-contact or NSF-listed. A compliant tank with a non-compliant gasket is not a compliant system.
Fiberglass for Potable Water
Fiberglass (FRP) tanks can be built for drinking water, but the tank has to be designed for it from the start. That means selecting a resin carrying FDA or NSF certificates, and steam-curing the finished tank so the interior is sealed and residual styrene is off-gassed. It is a specific certified procedure, not something retrofitted onto a general-purpose FRP tank.
How Tank Systems Builds for Food & Water
Tank Systems manufactures polyethylene tanks using LLDPE (linear low-density polyethylene) resins for FDA/NSF applications, produced by rotational molding as seamless one-piece structures. For potable water, ASTM D1998 is the standard covering polyethylene upright storage tanks. Tell us the product, the temperature, and whether the application is food contact or potable water, and we will match the resin, certification, and fittings to it. Contact us or request a quote to spec a food-grade or potable-water tank for your site.
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