Technical Deep-Dive: Selecting the Right Polyurea for Potable Water Applications
One of the most technically demanding and fastest-growing application segments in the polyurea industry is potable water infrastructure — cisterns, storage tanks, reservoirs, and water treatment facilities. This post covers the key technical and regulatory considerations for applicators entering this market.
Why Polyurea for Potable Water?
Polyurea has emerged as a leading choice for potable water infrastructure lining for several interconnected reasons. First, when formulated and cured correctly, polyurea is certifiable under NSF/ANSI Standard 61, which governs materials in contact with drinking water. Second, its spray-applied nature allows seamless coverage of complex geometries — corners, inlet/outlet penetrations, and irregular surfaces — where traditional liners often fail. Third, its high elongation (typically 300–600%) and tensile strength provide the flexibility needed to bridge minor substrate cracks without delamination.
NSF 61 Certification: What Applicators Need to Know
Not all polyurea systems are NSF 61-certified. As an applicator, it is your responsibility to verify that the specific polyurea system you are using — both the isocyanate and polyol components — carries current NSF 61 certification for the intended application. Certifications are system-specific and are voided if components from different systems are mixed. Request certification documentation directly from your material supplier and retain it in your project file.
Important: NSF 61 certification is specific to the finished product in its cured state. The application process itself — mixing ratios, substrate temperatures, film thickness, and cure time — must be controlled precisely to achieve the certified result. PolyOrgs recommends maintaining a job-specific Quality Control Log documenting all relevant application parameters for every potable water project.
Substrate Preparation for Concrete Tanks
For concrete cisterns and tanks, SSPC-SP 13 / NACE 6 (“Surface Preparation of Concrete”) sets the standard for substrate preparation. Key steps include:
- Repair all cracks, voids, honeycombing, and delaminated areas with structural-grade cementitious or epoxy mortar
- Achieve a minimum Concrete Surface Profile (CSP) of 3 using abrasive blasting, scarifying, or shot blasting
- Test for moisture content using ASTM D4263 (plastic sheet test) — most polyurea systems require substrate moisture below 4%
- Allow new concrete to cure a minimum of 28 days before applying polyurea
Application Parameters for Water Containment
Minimum film thickness for potable water tank linings is typically 60 mils (dry film), though many engineers specify 80–100 mils for large storage tanks. Apply in multiple passes to achieve uniform coverage, paying extra attention to corners and around penetrations. Use a 45° back-and-forth spray pattern to avoid pinholes and ensure complete coverage of all surfaces.
Holiday (pinhole) testing using ASTM D5162 low-voltage wet sponge testing is standard practice for all potable water linings. Document all holiday locations, repair, and retest before project closeout.
PolyOrgs Resources for Water Infrastructure Work
Members can access the full PolyOrgs Potable Water Application Standard, NSF 61 system directory, and sample QC documentation templates in the Technical Library. The new Potable Water Infrastructure specialty endorsement program includes hands-on training on all of the above topics.