Sewer flow monitoring will quantify I/I however it is like knowing a patient has a fever - there is something wrong but where? I/I location has largely fallen to the lot of CCTV inspection. This is a little like restricting a doctor to just using a stethoscope for disease diagnosis. It is very effective method for some diseases but not all. A targeted diagnostic tool, the equivalence of blood tests and microscopes in medicine, is required to provide the critical information of where the pipes leak before the I/I disease can be treated cost effectively.

CCTV produces an image of the pipe and is easy and quick to deploy compared with joint pressure testing - the only method, until now, that is capable of detecting most potential pipe joint leaks. However CCTV cannot "see" faulty pipe joints or service connections that are often the major contributors to I/I. Except for gross failure, the only time CCTV can detect a faulty joint is when water is "seen" flowing through it - this often only happens during the storm events when SOS's occur - not a time when CCTV is done.

This major shortcoming of CCTV to detect all potential pipe leaks goes a long way towards explaining why attempts to cure I/I tend to fall short and the pipe rehabilitation payback through reduced O&M seldom eventuates. Assessing the potential leakage of a pipe during a storm event requires the knowledge of all the pipe defects. All the pipes may leak but which ones leak the most is the critical question for cost effective I/I reduction.

All types of sewer pipe defects that are potential leaks are detected, located and measured by this tool. Electro-Scanning may also be used to characterize the cause of the defect such as a joint fault, structural collapse or service connection failure.
As with all good diagnostic tools, Electro-Scanning is fast, low cost, easy to use and provides immediate results.

Most sewer pipe materials are electrical insulators. A defect in the pipe that leaks water will also leak electrical current whether or not water infiltration is actually occurring at the time of the test.

Electro-Scanning a pipe is carried out by pulling an electrode, called a sonde, through the pipe and measuring the variation of electric current flow through the wall of the pipe, then through the ground to a fixed electrode on the surface.  The electrical current flow data and the position of the sonde in the pipe are displayed in real time on a notebook computer.

A computer program grades the size and type of each anomalous electric current flow and calculates the potential relative leakage for each manhole to manhole pipe section. An example of Electro-Scan results is shown above.

I/I can now be taken out of the chronic disease class. Electro-Scanning enables efficient and cost effective treatment programs to be designed that will pay-back through reduced O&M in a few years rather than tens of years or never.