South East Water is one of Melbourne’s three metropolitan retail water businesses. It is a state owned company that services over 1.3 million people throughout an area of 3,640 sq km. The water supply network consists of 8,400 km of water mains with 600,000 property service connections.

Identifying leaks quickly and cost-effectively is a key issue in South East Water’s commitment to water conservation. Solving the problem of thousands of litres of water literally going down the drain each year is crucial for the sustainability of the community, the environment and the water industry.

New pipelines and in particular existing mains and service lines can start to leak due to bad joints, deterioration, stress in the soil and corrosion. This could lead to more extensive damage and loss of precious water. Finding a leak and pin-pointing the location will have an impact on the extent of rectification works, environmental burden and investment.

‘us’ – Utility Services has many years of experience in undertaking proactive leak detection of water mains and service pipes in South East Water’s and other Regional Utility networks. The company said it is committed to the long term benefits to reduce nonrevenue water through leakage detection, pressure management, asset renewal and emergency response to asset failures.

The initial survey of water mains is carried out by using electronic listening sticks that will analyse unusual noise from a water main fitting or a water meter to determine the likely location of leakage. The operator will eliminate operational noise generated caused by normal usage.

Once a potential leak is evident, the specialist leak detection technician determines the exact location of the leak through data evaluation.

The ‘us’ preferred method of finding water leaks is a system called ‘Soundsens’ that was developed in the UK. It is a radically improved system that combines noise logging and leakage noise correlation into a single process.

The Soundsens approach is based on the deployment of highly sensitive and accurate loggers, called ‘pods’. The pods, which are time synchronised, record sound in short bursts lasting a few seconds. This recording is repeated multiple times to separate genuine use from suspected leakage. The duration of recording, the number of recordings and the dwell time between each data block is programmable and depends upon the pipe material in question, or whether the test is taking place during the day or at night.

The pods have an advanced digitally amplified accelerometer, which is capable of detecting lower levels of sound than can be expected from conventional designs, which simply correlate sound velocity between two points.

The data from each pod is transferred to a laptop, where a layout of the pipe work is graphically drawn using either GIS data or a simple sketch. The layout enables the software to both link and take into account the spatial relationship between the pods.

Once the layout is complete, the software uses proprietary algorithms to amplify the sound and filter out anomalies. Correlation takes place between each pod in the array and all of the others. The cross-correlation is unique to the Soundsens system and enables greater certainty in pin-pointing leaks as it discerns leak noise profiles from other water sounds.

All leaks are pin-pointed on the pipe layout diagram, tabulated and ranked in order of probability. The software will also show any correlations that should be subjected to further investigation. To help with this, the operator can listen to the sound using the software’s audio feature. The data files can be stored on a PC to make additional analysis or be used at a later date for reporting and tracking purposes.

As with any technical equipment, it is only effective in combination with the operators skills. ‘us’ have many years of experience in the field using this equipment with great, proven success in the water industry.

As the loggers don’t require a transmitter like the conventional correlator, the requirement of traffic management is less onerous as no transmitter is left in the road – requiring no traffic diversion during the correlation process.

As part of the company's commitment to water conservation, ‘us’ have used state of the art technology to manage the age-old problem of finding and repairing pipes that may be leaking below ground.

‘us’ has identified and repaired 104 leaks during 2007-08, which has saved approximately 124 million litres of water and have investigated more than 2,000 km of water mains for South East Water this financial year in the search for ‘hidden’ leaking water pipes.

A recent example – as shown in the pictures – was located in Wonthaggi, Victoria, where a cast iron flanged dog leg on a 100 mm AC water main was the reason for leakage. As a 300 mm concrete storm water drain was in the near vicinity, the water was flowing directly into the storm water system with no water coming to surface. It was apparent that the leak had been flowing for many months with a flow rate of 70 litres per minute.

The local development of ‘us’ award winning web-based consumption monitoring platform – HydroShare – is also playing a vital role to identify leakage on the customer site. Any sudden increase of continuous flow is immediately alarmed via exception reporting to email or phone SMS. Everything is clearly visible by just accessing the secure, customised website. This has resulted in massive savings or cost avoidance for customers.