Updated 29 October 2025

This is part one of a project to install a secondary water meter and automatic shutoff valve to my homes incoming water feed.

The first task was to locate the route my buried plastic (MDPE) water pipe takes to the boundary meter from the house, hopefully I can expose the pipe near to the garage.

The main reason for getting the meter near the garage was to enable easy connection to the Home Assistant interface and to ensure Wi-Fi connectivity to this.

The images show from the boundary meter, (mine on the right!), looking towards the house, whilst the other picture is looking from the house with the assumption that the pipe is buried in a straight line.

The water pipe is 25mm and does not have any buried tracer wires or tracing features, therefore, I cannot use any radio detection avoidance/detection tools to impose a signal.

Excluding Ground Penetrating Radar, I could isolate the water and disconnect the pipe at the stopcock, and from there insert a metal ‘fish’ into the pipes length, giving me the ability to impose a radio signal on this and track it with a Cable Avoidance Tool (CAT), as this was ‘invasive’ and practically, very difficult I opted for the second method.

This method involves connecting a pulsing solenoid valve to an outside tap which causes an audible ‘water hammer’ which can be detected with a sensitive microphone, this is called the ‘Thumper’ method.

Complete ‘Thumper’ setup, the 12v solenoid valve is from Aliexpress and is pulsed by the circuit contained within the enclosure.

With the water being ‘pulsed’, the next part was to detect to sound and trace the pipes path based on how strong the pulse sounds, bearing in mind that the pipe is buried at least 500mm (should be 750mm, but 500mm was to the base of the existing boundary meter chamber).

I bought a high sensitivity microphone and amplifier from Aliexpress for £23.99 which is incredibly good, I did clamp the circular microphone onto a piece of aluminum which had a length of stainless steel thin bar tapped into it, this allowed me to push deeper into the lawn in the hope of hearing the ‘Thumper’ noise.

Each time I heard an audio signal, I moved the probe back and forth to find the strongest signal and marked this with a flag, as you can see, the pipe veered off the straight predicted line.

Day 1 – Dig (13 Oct 25)

As it was raining slightly and I don’t want my back to go, I decided to take it easy with the digging.

I started with a spades width rectangle hole and went carefully as I didn’t want to damage any services, I did know that the edging stones were cemented in, but was unsure how far this went under the lawn.

I didn’t have to dig too far down (300mm) to expose the incoming mains electricity and gas on top of the surface water drain pipework.

I checked the black duct using the ‘Thumper’, but its the electrical supply cable to the house, I did dig another hole to the side of this one, but it just confirmed that the surface water drain carried on to next doors property.

Filled everything back in ready for round two!

Day 2 – Dig (17-19 Oct 25)

I moved 700m nearer to the meter from the first dig and decided to basically trench across the lawn to give me a good chance of locating the pipe.

After digging 800mm deep and 1000m across, there was still no sign of the water pipe and using the ‘Thumper’, I could hear the rhythmic beat using the high gain microphone, but was unable to ‘hone’ in to a strong signal.

I could only conclude that the vibrations caused by the ‘Thumper’ was being transposed onto the neighbours water pipe and it was this I was detecting, rather than mine!

Day 3- Dig (20 Oct 25)

I wasn’t sure what to do at this point, I did ask for advice on my towns local Facebook page and had a really helpful reply, following this up, I was given a contact number of an ex-Anglian water guy, but the problem was unless the pipe was leaking detection was not possible with the tools and methods he had.

Prior to posting on Facebook a chap at ‘Man Shed’ suggested using water dowsing to find the pipe, when I got home, I was skeptical, but gave it a go with two bits of brazing rod, and blow me it gave an indication.

The far blue flag shows the location of the water meter, so I walked at 90⁰ to this across the grass and drive and plotted when the rods crossed, repeating this I finally ended up with the second blue flag and a box location to dig in the hope I find the pipe.

I did also appear to pick up a sewage pipe which traverses across the front of my house.

Digging down through the drives hardcore I’ve come to a chunk of concrete which could be discarded builder waste or, more hopefully, a cap over the water pipe ducting.

Day 4 – Dig (21 Oct 25)

Oh well! My hopes were dashed when the concrete was broken away and I checked the area with the microphone for signs of an audible signal, but nothing.

No choice but to refill the hole and nip out and get some MOT type 1 to get the levels back, once compacted and covered over, nobody would know.

Plan ‘B’

Although the microphone pick up the ‘Thumper’ hydraulic pulses, I decided to build a ‘Pipe Knocker’ which simply hits the pipe using the same controller as the ‘Thumper’ to control a small solenoid, this will be attached directly onto the pipe from the meter.

My idea is that should allow me to hear a stronger pulse working from the meter to the house, rather than from the house to the meter.

My 25mm feed is on the left and my neighbours is on the right, both directly buried at a depth of 400mm and protected with a layer of sand, I think that due to the close proximity to each other, its not going to be easy to be sure which pipe I’m tracing which ever method I use.

The nuclear and last option will be to expose more of the pipe and cut the pipe to insert a wire with an imposed signal on it that can be accurately tracked by radio detection, giving me a definitive location to dig.

Day 5 – Dig (22 Oct 25)

Bit more digging to break out the concrete giving greater access to the water pipe, this is in preparation to cut the pipe and use trace equipment to find the pipes route.

I tried the stethoscope from Amazon to listen for the ‘Thumper’ bit it didn’t work effectively for this application, there was a faint noise, but this soon disappeared as I moved further into the lawn from the meter and the main problem with the high sensitivity microphone was determining any form of direction as the sound generated from the ‘Thumper’ is omnidirectional, therefore, I abandoned the ‘Pipe Knocker’ idea.

Last ditch attempt was to install an LED bar graph on the audio output of the microphones output.

The idea was to give me a visual indication of the strength of sound received by the microphone and enable me to ‘hone’ in the pipes route, alas this failed as the voltage changes to the bar graph were indicated fine for large vibrations but not with the low vibration signals.

Day 6 – (24 Oct 25)

Ok, I admit defeat, I’ve hired the following equipment from HSS:

1 – Cobra with a single core wire tracer which I will attach the cobra, this will be inserted inside the open end of my 25mm water pipe and enable detection of pipe route and depth by the C.A.T.4+

2 – C.A.T 4+ radio detection device, tuned to the Genny frequency this device will determine the location and depth of the wire tracer within the plastic pipe.

3 – Genny4 transmitter imposes a radio frequency on the tracer wire suitable for the C.A.T. 4+ to detect.

4 – I used Amazon to get a WRAS approved direct bury suitable Plasson 25mm Slip Coupling, this will be used to join the MDPE water pipe where it will be cut to allow the cobra and tracer wire to enter the pipe, a slip coupling will be used as pipe movement is restricted, being fixed points at each end. Another plus to a slip coupling is that pipe inserts are not required, so water flow will not be impacted by any restrictions caused by the coupling.

Day 7 – (27 Oct 25)

I don’t think HSS could have cocked this up any better, the whole experience was a pain in the arse, moving on…..

Cutting a long story short the depth of the water pipe at my preferred sub meter location was ~1.5m deep, so no wonder I could find it with my 800mm trench and water dowsing was a right bum steer!

Breaking this down:

The slip coupling length was marked on the pipe before cutting after I had double checked I was on the correct pipe, the house stop cock was off and that the streets isolation valve was holding.

I decided against using the hired duct rod (Cobra) until I had tried using a plastic conduit fish tape with a wire attached to push deep into the pipe, this worked effectively with little resistance.

Once sufficient wire was pushed into the pipe to where I would prefer the chamber for the sub meter to go, I attached the Genny4 and with the CAT4+, I traced the route and approximate depth of the detected wire inside the pipe.

Slip coupling installed and leak tested.

So that’s the end of this blog on finding a plastic water pipe, as you can see I tried a number of different non invasive techniques, but in the end a CAT and Genny was the only way.

The follow on from this blog is one about installing my sub meter and can be found HERE.