NSF/ANSI 61 and Why Your Tank Repair Product Matters
By Marisol Vega, Municipal water operations manager. Reviewed by Dana Whitcombe, technical reviewer.
Potable Water Tank Inspection & Cleaning | Wastewater & Sewer Diving Last April, I pulled a chunk of peeling epoxy off the wall of a 1.5-million-gallon elevated tank near Katy, Texas. The stuff had been sprayed on just fourteen months earlier. It smelled like solvent and came off in sheets. My crew had barely drained the tank before I was on the phone with the contractor, asking one question: is your coating NSF/ANSI 61 certified? Dead silence. That's the thing. In this job, we drink the water we store. We've got 40 finished-water storage tanks in the system, and every one of them has to meet state and federal drinking water rules. Texas requires an annual inspection of potable water storage tanks under 30 TAC 290.46(m)(1). That's not a suggestion. And the material you put inside those tanks matters as much as the structural steel.
What NSF/ANSI 61 actually covers
NSF/ANSI 61 is the standard that sets health effects requirements for materials that come into contact with drinking water. It's not a paint performance standard. It's a leaching test. Products are immersed or extracted and analyzed for a range of contaminants, from metals to organics to disinfection byproduct precursors. If a product passes, it's listed for a specific use, water temperature range, and surface area to volume ratio. That last part is critical. A product certified for a pipe liner may not be certified for a tank floor. A coating that's fine for cold water may not be fine for 120-degree water. So when a contractor says 'it's potable grade' or 'it's safe to drink' without showing you the NSF listing, call it what it is: a red flag.
Why repair products get sneaky
The sneakiest problem I've seen isn't a contractor using a non-certified product on purpose. It's a contractor thinking any epoxy is the same as the certified one. They show up with a generic 'potable water safe' coating from the hardware store. It might even have a certification letter from some lab nobody's heard of. But if it's not in the NSF/ANSI 61 listing, I can't accept it. Why? Because the standard is a measured thing. The test methods are documented, the pass/fail numbers are public, and the responsibility for keeping the listing updated falls on the manufacturer. When you see that NSF logo on the label, you're not taking the coating's word for it. You're taking an accredited third party's word for it. In Texas, your annual tank inspection is a compliance event. If I can't show the inspector the product data sheet with the NSF/ANSI 61 logo, I'm writing a corrective action report. That costs money, time, and trust.
How I check before I approve a repair
I keep a spreadsheet of approved products. It's not fancy, but it works. Each row has the product name, manufacturer, NSF/ANSI 61 listing number, the date I verified it, and the temperature range it covers. For a tank repair, I look for three things. First, a current listing on the NSF website or the manufacturer's directory. Second, the specific product name and color — because some manufacturers have multiple versions that look identical. Third, a statement from the applicator that they'll follow the manufacturer's application requirements. If any of those are missing, I stop the job. One digression: I know some operators who only use two-component epoxy systems for longer life, but I've seen single-component coatings last a decade when applied right. It depends on the plant, the water chemistry, and how well you prep. The NSF standard doesn't tell you which is more durable. That's on you.
The documentation trap
The biggest trap is thinking the certification is forever. It isn't. Manufacturers reformulate, listings expire, and sometimes a product gets pulled from the market. A coating that met NSF/ANSI 61 in 2018 might not have been re-certified after a change in raw materials. I've been handed a data sheet with a stale date and told 'it's the same thing we used last time.' It might be. But 'might' doesn't survive a state inspection. Keep your records tight. Every repair job should end with a binder of documents: the product data sheet, the certificate of compliance, the application temperature and humidity log, and the curing time. That binder is your proof to the inspector that you didn't just trust a guy with a spray gun. You trusted a standard.
Frequently Asked Questions
Does NSF/ANSI 61 apply to all tank repairs? If the material touches drinking water, yes. Structural repairs outside the tank don't need it, but any coating, liner, sealant, gasket, or fitting in contact with the water does. Can I use a product that's not NSF 61 certified if I flush the tank? No. The standard is about continuous contact, not initial rinse. Flushing doesn't change the chemical compatibility. How often do I need to inspect a tank? In Texas, annually. Other states may follow AWWA M42, which recommends every three years. Check your state rules. What about AWWA C652? That's disinfection of water storage facilities. NSF/ANSI 61 is about materials. Both matter, but they're different.