Since 2020, Urban Utilities (UU) has been replacing older water meters in many townhouse and multi-residential complexes with new Octave ultrasonic meters. While these meters are highly accurate under normal conditions, in some setups, particularly where there is no backflow prevention device on combined fire service lines, they can produce false readings.
This means that some residents are being billed for water they haven’t actually used. Pressure fluctuations in the plumbing system can trigger the meter to record phantom usage, resulting in unfair and inflated bills.
The issue is not caused by residents. It stems from the combination of meter sensitivity, system pressure changes, and the absence of proper backflow protection.
Installed against manufacturer recommendations
Manuals and correspondence with the manufacturer have revealed that UU have installed these meters against their recommendations.
“Where the ‘Forward only’ Volume Display option is used, RWC recommends the use of appropriate backflow prevention to prevent reverse flow through the meter.”
Excerpt of letter from manufacturer
“Due to the high sensitivity of ultrasonic measuring principals, it is recommended that a testable backflow device is installed downstream of the meter to provide hydraulic stability. The recommended backflow device should be installed between 2 and 10 pipe diameters from the meter outlet. Failure to do so may result in movement within the measuring chamber leading to backflow measurement. RWC is unable to support backflow diagnostics where this advice is not followed.”
Octave Ultrasonic Water Meter Manual
This is affecting complexes that were built before the new metering guidelines were introduced around 2020.
UU have stated that residents are required to upgrade the plumbing in the complex to install a backflow prevention device, at the cost of about $10 000. Meanwhile, they are charging residents for water they haven’t used.
The SEQ Water Supply Code states:
Designs that were substantially commenced prior to a new edition coming into effect will not need to be amended to meet the new standards.
Residents should not have to upgrade the plumbing at their cost due to the type of meter UU have installed.
The Octave ultrasonic meter is not fit for purpose.