Detecting Leaks

[Ben Minutoli]

Detecting Leaks by Mark Quartermiane

Where do you think the leak is? This is the first question a person asks when a leak detection contractor arrives at their premises.
Perhaps they should have called a clairvoyant instead of a plumber.
It’s the plumber’s job to give the customer confidence that he has the ability to find the leak and although there are various methods to detect leaks, I believe the following four steps are simple and effective.
Step 1
Locate the water meter and establish what the flow rate or water loss is, this will determine the size of the leak.
If the customer is going to apply for an ex-gratia payment from the relevant water utility, they will need the meter number, meter reading, flow rate and a brief description.
Customers often don’t realise they can make a claim, so gathering this information is vitally important.
Step 2
You will need to determine if the leak is on the hot or the cold water service. As detecting leaks is an inexact science, it is best to use a process of elimination. The water leak noise is constant and in most cases the leak will only get bigger. You will need to trace this constant noise to locate the leak. There are many tools that can help but they will not solve all leak locations.
Tell the customer up front and do not exaggerate your abilities, instead always strive to over deliver, above the customer’s expectations.
Step 3
Ask the customer for background information; they may already have part of the solution without realising it, but it is your job to verify it, as it could be totally wrong. Do a visual check for things like signs of water in wet areas, water lying on the ground, a green patch in an otherwise dead lawn; these are good places to start.
Step 4
If you are already doing some or all of these things, just be consistent and continue to develop your method for detecting leaks as you become more experienced. Learn to identify the different scenarios that reoccur and apply your knowledge to what evidence you gather.
If you are consistently spending too much time looking for leaks and not being very successful, it’s time to call in a Water Leak Technician.
Unfortunately, in Australia there is no qualification for this work, unless you carry out the repairs, in which case you have to be a licensed plumber.
There are people who specialise in carrying out domestic and commercial leak detection and if this is something you feel confident to pursue, then be prepared to spend a minimum of $10,000 for start-up equipment plus ongoing development costs.
You will need to assemble a basic leak technician’s tool kit containing the following:
As a human’s ear can only hear a short range of sound, the acoustic microphone enables you to amplify the various environmental noises and filter them out to expose the sound of the water leak. This equipment is called a listening stick. It was original made from wood then metal and now they are electronic. You simply move around the house sampling sound values and comparing them.
Most times in a house a plumber can track the plumbing system. If this is not possible various devices are needed to locate where the water service runs. This equipment is called a pipe and cable location unit, which is an electromagnetic field locator.
You will hear some leak noises over a wide area, so you will need to listen directly over the top of the pipe, especially if you are listening indirectly through the ground.
It will take you around six months of trial and error to understand electronic leak detection and after about two years you should be reasonably proficient.
A general rule of thumb is if you have not found the leak after two hours ask the customer what he or she would like to do. You will need to give them some options.
Quantify the Leak
If possible catch the leaking water in a cup or measuring jug and time how long it takes to catch a certain quantity of water. For example, a flow rate of 100 ml per minute is equivalent to a small glass of water.
Here is a tip to remember; do not give an opinion of the leak location, until you can see a sample of water.
Detecting a leak can be costly and you need to be careful with the customer’s money.
You should always attempt to minimise the damage by pinpointing the leak. This can be done using an earth probe or prodder (preferably insulated against electrical hazards) before digging a hole and disturbing pavement. Or use a long series drill bit to verify the leak location. Work on a target area of around 300 mm in diameter although it is not always this accurate.
Terminology
Leak detection means the mechanical vibration (frequency) that the leak makes as it leaves the pipe, it is heard mainly through the wall of the pipe and through the column of water.
Velocity is the speed at which the sound (frequency) travels down the pipe.
Unfortunately, the cost of water is still undervalued but this will change as the real charge for desalinated water kicks in, so you have to way up the economic cost of searching for the leak.

Bio: For more information on leak detection, contact Mark Quartermaine, Leak Detection Technician and accredited Water Wise Auditor.