The gas station tightness test verifies that underground tanks, pipework, sump chambers, and fill points are leak-free. It is the primary tool for preventing fuel-contaminated groundwater — and the ANP’s most enforced environmental protection requirement. The Petrol Group team explains what is required in 2026.
What must be tested
Underground storage tanks (USTs), fuel supply pipelines (tank to dispensers), sump chambers (containment boxes under dispensers), fill point covers and access chambers, and oil/water separator connections.
The nitrogen pressure test method
Most common method: nitrogen injection at controlled pressure (0.5-1 bar), 30-60 minute stabilization, pressure reading. Any pressure drop exceeding tolerance indicates a leak. Test duration: 4-8 hours per tank. Only ANP-accredited companies may issue legally valid test reports.
Testing frequency required
USTs: every 5 years minimum (more frequently if required by state environmental agency). Flexible pipelines: every 3 years. Sump chambers: every 2 years. After any tank repair or product change: mandatory before returning to service.
FAQ
What happens if the tightness test fails?
Mandatory notification to state environmental agency within 24 hours. Isolate and shut down the failed equipment. Commission confirmatory investigation. Present remediation plan if contamination is confirmed.
See: ABNT standards and ANP compliance guide.