Module 6: Water Supply Pipes Detection, investigation, repair, ownership

Trainer note:

Pipe Tracing – We First have to investigate the location of the pipe. Water seen at the surface is not necessarily the point of leakage as water will always flow with gravity.

Metallic pipes can be traced by attaching a signal generator which sends a signal along the length of the pipe and this is detected above ground by a receiver tuned to the same frequency.

Non Metallic Pipes cannot conduct the transmitted signal; this is overcome by

a) Inserting a tracer wire inside the pipe, and sending the signal along the wire, or

b) Using a device to send alternating pressure or sound waves through the pipe, and the sounds are detected above by sensitive ground microphones.

Leak Detection

a ) Ground Microphones

When water escapes from a pipe under pressure, it creates a noise – metallic pipes

create a higher frequency sound, plastic pipes create a lower sound. These sounds

are picked up by sensitive ground microphones, with high and low frequency filters.

b ) Leak Noise Correlation

With correlation, the sound is electronically measured by microphones at two points, (usually at the boundary stopcock and the internal stopcock). The sounds are assessed by computer and the sound peak is calculated from both points.

c ) Tracer Gas

An inert and harmless tracing gas, usually 95% Nitrogen and 5% Hydrogen is injected into the pipe. Hydrogen molecules are extremely small, and as they exit via the leak, they rise and permeate through the layers above, whether soil, concrete or tarmac. They can then be detected by extremely sensitive sensors, indicating the area of leakage.

Trainer note:

If the leak detection has been done and the leak is suspected to be under the property an excavation should be done at the point of entry to prove this.

Trainer note:

Excavation – as with drainage claims engineers are able to isolate the supply dig down and carry out a point repair at the area that is damaged.

Moling – the device is launched from a small pit, compressed air drives the device which punches its way through the ground to a receiving pit leaving behind a ducting which now pipe can be pulled through. This saves excavation and reinstating costs

Trainer note:

The Water board are responsible for the repair

and maintenance of the water mains, which

carry large amounts of water from the treatment works to homes in the UK.

Homeowners are responsible for the pipe that supplies their individual properties.

Properties are connected to the water main through a pipe, the ownership of which can be divided into two parts:

The 'communication pipe'This part of the pipe is our responsibility and is located under the pavement or road, connecting

to our main.

The 'supply pipe'This part of the pipe is the homeowner's responsibility and is located beyond the

pavement, connecting to the property's internal pipes.