Tank Testing – Detecting Manway Gasket Leaks and Preventing Water Ingress

A precision tank test that can detect manway gasket leaks and prevent water ingress is critical to the reliable operation of any generator fuel tank. At Flowco Australia, our Precision Tank Test delivers the most accurate method for identifying leaks and water ingress in backup generator fuel systems. In critical power applications—such as hospitals, data centres, and telecommunications facilities—just one undetected leak can threaten emergency power availability when it is needed most. One of the most common and preventable causes of water contamination in these tanks is a damaged or failing manway gasket.

Over time, manway gaskets can deteriorate due to constant exposure to fuel vapours, UV light, and environmental conditions. When the seal between the manway cover and tank is no longer watertight, water from heavy rain, wash-downs, or surface flooding can enter the tank. This is not simply a maintenance concern—it is a direct risk to the reliability of your backup generator system.

Why Manway Gasket Leaks Are High-Risk for Backup Generators

In backup generator applications, water ingress can have an immediate and costly impact. Unlike retail fuel systems, where water contamination might first be noticed in vehicle performance, a generator tank contaminated with water may cause the generator to fail during the very first minutes of a power outage.

Water in a diesel tank promotes microbial growth, leading to sludge formation and filter blockages. This not only increases wear on pumps and injectors but can prevent the generator from starting at all. Additionally, water accelerates internal corrosion, weakening tank walls and pipework. In severe cases, corrosion can compromise the tank’s structural integrity, resulting in environmental contamination and costly replacement works.

Regulatory compliance is another factor. Under UPSS and EPA regulations, fuel tanks must be watertight. Water ingress from a faulty manway gasket breaches these requirements and may result in penalties, remediation orders, and unplanned operational shutdowns.

How the Flowco Precision Tank Testing Pinpoints Leaks

Flowco’s Precision Tank Test uses advanced volumetric measurement technology capable of detecting even the smallest variations in tank volume. The process is precise enough to measure changes as small as 0.38 litres per hour, making it ideal for identifying slow leaks and subtle water ingress points before they cause operational issues.

The testing process includes isolating the generator tank from the fuel supply line, stabilising the fuel to eliminate the effects of temperature changes, and conducting a detailed measurement cycle. If we detect product gain following rainfall, this is a clear indicator of water ingress. Our technicians then carry out a targeted inspection, often revealing compromised gaskets or loose manway covers as the source.

Real-World Example – Preventing Backup Generator Failure

During routine compliance testing on a backup generator diesel tank, Flowco’s Precision Tank Test identified small manway gasket leaks that matched the customer’s reports of a subtle but consistent water level increase that could not otherwise be explained. Unlike sudden water ingress events caused by extreme weather, this was a gradual change — the kind of hidden problem that can go unnoticed for months or even years.

Our testing pinpointed the source: a hardened and shrunken manway gasket. After years of exposure to temperature extremes and fuel vapours, the gasket had lost its flexibility and sealing capability. This allowed rainwater to seep past the manway cover in small increments whenever surface water pooled around the lid.

While each ingress event was minor, the cumulative effect was significant. Over time, water accumulated at the bottom of the tank, creating conditions for:

• Microbial contamination – Water and diesel create an environment where bacteria and fungi thrive, forming sludge that can clog filters and damage pumps.

• Accelerated corrosion – Standing water exposed the tank bottom and internal fittings to ongoing corrosion, risking structural failure.

• Fuel quality degradation – Contaminated diesel can reduce combustion efficiency, impair generator performance, and cause failure during start-up.

In backup generator applications, this type of slow deterioration is particularly dangerous. While the generator may still operate in routine tests, prolonged water exposure can cause it to fail under the load and stress of a real outage.

By detecting the problem early, Flowco was able to:

• Replace the manway gasket with a high-quality, fuel-compatible seal

• Perform a Tank Clean & Fuel Polishing service to remove water and microbial contamination and restore the tank to a clean, dry state

• Return the fuel to full operational quality

• Prevent long-term damage to both the tank and the generator’s fuel system

This intervention ensured the generator would deliver reliable emergency power when required, maintained full EPA and UPSS compliance, and avoided the costly consequences of unexpected failure — including business disruption, equipment damage, and emergency repairs.

Flowco’s Precision Tank Test doesn’t just detect obvious leaks — it uncovers the small, slow, hidden problems that can lead to major operational failures in the future.

Why Flowco’s Precision Tank Testing is the Best Defence

Our method is not just about finding leaks—it is about preventing operational, financial, and compliance problems before they occur. With nationwide coverage, fully trained and certified technicians, and EPA-compliant testing procedures, Flowco provides accurate, actionable results backed by comprehensive reporting suitable for both operational and audit purposes.

For businesses relying on backup power, early detection of manway gasket leaks is critical. A single incident of water ingress can compromise emergency readiness, damage expensive generator equipment, and result in significant downtime. Our Precision Tank Test ensures your fuel system is ready for any outage, with clean, uncontaminated fuel available at a moment’s notice.

Book Your Precision Tank Test Today

Protect your critical power assets and maintain compliance with Flowco’s industry-leading testing service. Contact our team today to schedule a Precision Tank Test for your backup generator fuel tanks and safeguard your site against water ingress risks.

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