Correct Water Level:

A Critical Compliance Check for Fire System Reservoirs

Are you certain your fire water tank is full and ready for action?
Fire protection systems are engineered to operate for a specified duration at a defined flow rate. That performance is only achievable if the reservoir is maintained at full design capacity. Anything less can compromise system effectiveness and place building owners at risk of non-compliance with legislation and relevant standards.

The Hidden Risk of Inaccurate Water Levels
At WTI, we have attended sites where fire water reservoirs were filled to as little as 20% of their required capacity—often without the owner’s knowledge.

In many cases, a compounding issue was not the tank itself, but a faulty or inappropriate water level indicator that did not alert the administrators Fire water tanks and their associated equipment represent a significant capital investment. Yet a relatively inexpensive component—the level indicator—can undermine the performance of a system worth millions if it is not functional or fit for purpose.

Common Failures in Water Level Indicators

Jammed or broken indicators
Many level indicators rely on water-borne moving parts. Over time, these components can corrode, seize, or become obstructed. Weights may catch, floats may stick, and indicators can jam entirely. The result is a tank that appears full, while the actual water level may be slowly dropping due to evaporation or minor leaks.

Indicators not fit for purpose
Dipstick-style gauges are a common example. These typically use a visible ball mounted on a metal rod. In exposed locations, the rod can bend in high winds and jam. More critically, this style of indicator does not measure the entire usable water volume above the anti-vortex array, as required by NZS 4541:2013, Clause 6.6.3.3. Similarly, sight glasses installed on very tall tanks can be impractical—if the top of the sight glass cannot be viewed safely from ground level, it cannot be reliably monitored.

Due Diligence Starts with the Right Equipment
Ensuring compliance is not just about having a tank on site—it is about knowing, with confidence, that it contains the required volume of water at all times. Selecting a compliant, reliable level indication system, and maintaining it as part of routine inspections, is a simple but essential step in demonstrating due diligence. With the right equipment and proactive maintenance, building owners can be confident their fire water reservoir remains ready, compliant, and capable when it matters most.

Previous Blog