Water piping disintegrating!

Submitted: Tuesday, May 12, 2026 at 20:30
ThreadID: 152498 Views:619 Replies:10 FollowUps:9
G'day all....some weeks ago I discovered a leak from the hot water pipe in our Jayco Outback poptop....it was under the 'van at the rear nearside corner....it was a tiny hole in the pipe and a squirt was coming out...as it is located behind the wheel I assumed it may have been hit by a stone...we had just returned from a trip out west....today, I noticed another leak!...almost it exactly the same spot....a close inspection showed another squirt....thinking this was quite odd I cut a section from the hose and gave it a close inspection. I was horrified to see that the hose had a multitude of fine cracks!....while there appeared to be only one leak I found that if i bent the hose it simply cracked in two in my hand!
Please refer to the attached photo.
The pop-top is not new, 13 yrs old actually, and we have towed it all over Australia for 58'000 km....however the hose in question has not been exposed to the sun and its security, its connection to the underside, is good.
The hose is typical as used in many caravans these days, I assume produced by John Guest. The blue cold hose, in the same location appears unaffected.
My obvious concern regards other locations of the hose, in many places the hose travels internally in some cupboards and in behind the shower cubical...the two leaks I mention above were relatively easy to get to and repair, I may not be so lucky next time.
Despite being caravanners for many years I have never seen or even heard of this issue before...I would appreciate any comments

Paul....Lockyer Valley Queensland.
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Reply By: Phil F - Tuesday, May 12, 2026 at 23:50

Tuesday, May 12, 2026 at 23:50
I Think you have done well to have the pipes last 13 years, as I had to replace my water lines a couple of years ago so they were a couple of years short of that period and was told by the repairer I was lucky to have them as long as that.

I patched odd section a couple of times along the way.

Would be worth considering replacing they system as you may find the leaks will become more prevalent and probably not at a time convenient to you. Either that or cart some repair kit material with you.

Good luck

Regards - Phil
AnswerID: 649217

Follow Up By: Sundowner2 - Wednesday, May 13, 2026 at 08:52

Wednesday, May 13, 2026 at 08:52
Thank you Phil....your reply agrees with the information I have so far, the constant thermal expansion and contraction being the cause.
And yes I have carried short sections of hose and the necessary fitting's for repairs for some time but never did I realize that some day the entire hot water hose system would need replacing!
While it will be relativity easy to take out much of the old and replace with the new my concern lies with some areas that will not be easy...I speak of course of where the hot water hose runs from under the van and up to the shower....in between the fibre-glass and wall, access to the the hose there may require removal of the shower cubicle, not cheap!

I guess I am fortunate that the issue has been discovered before any major damage has been done.
Woe is me.

Paul
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Follow Up By: Phil F - Wednesday, May 13, 2026 at 09:42

Wednesday, May 13, 2026 at 09:42
Hi Sundowner

I was lucky enough to have a vent fitted close to the shower plumbing which allowed access to replace the hot water line. Tight fit but saved major repair job.

Here is another theory - RED is the first colour to fade in paint, perhaps it may apply in plastics as well??

Regards - Phil
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Reply By: Member - John - Wednesday, May 13, 2026 at 06:51

Wednesday, May 13, 2026 at 06:51
The caravan place I use said that they don't stock it anymore, only blue and black as the red one didn't last
John and Jan

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AnswerID: 649218

Reply By: Mikee5 - Wednesday, May 13, 2026 at 08:19

Wednesday, May 13, 2026 at 08:19
The pipes under my caravan also went brittle after many years. I have a theory, mad or not, that the chemicals in the car exhaust fumes reacted with the plastic pipes over the years as they blow under the caravan. I recently had to replace all the piping.
AnswerID: 649219

Follow Up By: Sundowner2 - Wednesday, May 13, 2026 at 11:30

Wednesday, May 13, 2026 at 11:30
Mikeee5, I dont believe there are any chemicals in exhaust emission gases that could have an adverse reaction to polymer, and my Triton that the exhaust pipe exit on the off side, the crook hose is on the near side....thank you for your input anyway
Cheers
Paul
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Reply By: Peter J4 - Wednesday, May 13, 2026 at 08:28

Wednesday, May 13, 2026 at 08:28
There was also a lower quality pipe available that while it looked the same wasn't the same quality as the JG pipe.
AnswerID: 649220

Reply By: Peter_n_Margaret - Wednesday, May 13, 2026 at 08:39

Wednesday, May 13, 2026 at 08:39
There is no guarantee that the hose you have is genuine John Guest.
Even if it is, the standard pipe has limited capability when used for hot water. From memory, 70C is the maximum.
There are other hoses (including John Guest brand) made specifically for hot water use. Same issue applies to the hose fittings.
Most that I have come across (both hose and fittings) are white and they cost quite a bit more than standard cold water versions. They are also stiffer.
Cheers,
Peter
OKA196 motorhome
AnswerID: 649221

Reply By: Sundowner2 - Wednesday, May 13, 2026 at 09:01

Wednesday, May 13, 2026 at 09:01
Thank you to all who have responded.....as noted it is likely the hose in question is not genuine John Guest. Would Jayco install genuine hose that will at least last the warranty out, or would they install the good stuff?. (A rhetorical question)

Also interesting to hear that the black hose is better. I did think t it amazing that in this, space age, we dont have such hose fit for purpose.

We have been caravanning for over 45 years and this is the first time I have come across this issue, we have had seven caravans but sadly, in hindsight, this one is our first with a hot water system...lol

Paul
The Lockyer Valley
Queensland.
AnswerID: 649222

Reply By: Member - Jim S1 - Wednesday, May 13, 2026 at 09:30

Wednesday, May 13, 2026 at 09:30
If replacing all affected hose , is there any chance of attaching a string as you pull out the old hose , so that it can be used to pull the new hose through the hard to get at areas ?

Cheers
Jim
"If you have a garden and a library, you have everything you need", Cicero

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Follow Up By: Sundowner2 - Wednesday, May 13, 2026 at 20:36

Wednesday, May 13, 2026 at 20:36
G'day Jim, yes I have considered that and I understand the professional repairs use similar ideas....it is possible to join the old and new hoses together and gingerly feed them through...I see today that where the shower tap combo fits to the wall in the shower cubicle it is on a panel, with 4 screws..removing this will likely help...and this spot was my biggest concern..removing the shower itself to get to the hose would probably cost more than the van is worth.
If you care to read the responses to this issue below you will see how it has finished up

Thank you for your response.

Paul
Lockyer Valley
Queensland
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Reply By: Allan B (Sunshine Coast) - Wednesday, May 13, 2026 at 10:18

Wednesday, May 13, 2026 at 10:18
.
Hi Paul,
John Guest tubing is LLDPE (Linear low-density polyethylene) which is more durable than some other polymers. It is available in several colours but only the black is UV stabilised, red being the colour most affected by UV.
It could be possible that some manufacturers (China?) may use the slightly cheaper and weaker LDPE polymer.
Although your problem tubing is under the van it may receive some (15%) UV reflected from the pavement. 13 years of exposure could be enough to produce failure. Is your point of tubing failure close to the side of the van?
In general, it is better to use all black tubing. After all, it is not difficult to differentiate hot & cold pipes when installing by wrapping a little red PVC tape near the ends.

As to replacement of installed tubes, in most cases it is possible to securely connect the end of a new tube to the old tube and use the old tube to draw the new tube in without having to dismantle cupboards or wall sheeting.
Cheers
Allan

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Follow Up By: Sundowner2 - Wednesday, May 13, 2026 at 12:18

Wednesday, May 13, 2026 at 12:18
Allan, thank you for your response, Can I say that responses like yours, and others, is testament to just how useful these forums can be.

This morning I spent some time under the van, flashlight in hand.
The cold hoses are black in color, not blue as I may have said. The hot water, where it enters and exits the HWS (Suburban) is white..under the van the white hose becomes red.
Once my initial shock, where my first thoughts were to simply sell it for whatever I could has passed I have been looking at the practicalities...as I mentioned my biggest fear was should the damage that would result if a leak developed behind a wall, or worse between the wall and the shower cubicle...looking today I see that the shower combination tap actually sits on a panel about 200 x 100 mm and held there by four screws, I am sure that once that panel is removed I would have a chance of feeding new hose up from under the floor which is directly below and only around one meter away.
Having said all that I did go over the underfloor red hose, from the HWS all the way to the rear and I was unable to find any of the cracking visible in my photo. The cracking seems to be restricted to a shortish section...maybe 2 meters in length as it runs across and secured to a chassis rail and between to John Guest connectors.
The ensuite hand basin combo tap, and the galley sink both have short lengths of the red hose coming up from the floor and connected to typical reinforced flexible hoses, they too should be easy to replace the red hose.
I note too that the little red clips that secure the John Guest connectors, designed to prevent inadvertent disconnection, despite costin a few cents each are not present anywhere in this Jayco...I am very aware of the strange things that vibrations can do, especially on Western Queensland corrugations!
Thanks again.
Paul
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Follow Up By: Allan B (Sunshine Coast) - Wednesday, May 13, 2026 at 13:01

Wednesday, May 13, 2026 at 13:01
Paul,
You say…."The cracking seems to be restricted to a shortish section...maybe 2 meters in length as it runs across and secured to a chassis rail and between to John Guest connectors."
Could it be that hose has been replaced at some time and an inferior grade product fitted? If so then simply replacing it with quality LLDPE black hose may be your solution.
Unless you detect weakness in hoses within the walls od the van it would seem un-necessary to replace these. If you do attempt to replace any hoses within the walls you would be wise to heed my earlier recommendation of not pulling out the old hose unless the new one is attached to it. The hoses are normally installed before the linings are fitted and frequently routed through holes in the frame. Once the old hose is removed it can be difficult to thread the new hose through holes that are not directly lined up. I suggest that the new hose is joined to the old hose using a JG straight connector and a lock clip or taping over the release ring as it can easily be depressed while dragging the connector through a frame hole.
Cheers
Allan

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Reply By: Sundowner2 - Wednesday, May 13, 2026 at 19:49

Wednesday, May 13, 2026 at 19:49
Allan, thank you for that....it is possible that the 2m section of hose may have been replaced at some stage....and, as I said, today I have been over the red hose, where I could access it throughout the van and did not find any evidence of the cracking as seen in my photo, if present it would have been readily felt.
Today I replaced the damaged section and I pressure tested the van for most of the day, firstly by running the Shurflo 12VDC pump...as you would know the pump will shut off once the internal water pressure reaches a pre-set number, I think perhaps 40 PSI...at that point I left the pump energised for about 3 hours, listening carefully for any tell-tale pump noises, and checking for any leaks, I heard and found nothing.
I then turned the pump off for another 4 hours after which I reenergised it and was happy to hear no pumping action, the pressure had been retained..from this I concluded the entire water system to be sound. Would you agree?
At this point in time we think we will take no further action but going forward our plan is to always ensure the water pump is turned off after use, something we generally do anyway, in addition we will remember to turn off the shore mains supply should we be in a caravan park and go away from the caravan.

Again, thanks for your assistance.
Paul.
AnswerID: 649225

Reply By: PeterInSa - Thursday, May 14, 2026 at 20:53

Thursday, May 14, 2026 at 20:53
Re (going forward our plan is to always ensure the water pump is turned off after use,)
We only Turn our pump off,…. Overnight, When Travelling, when away from the van eg Shopping.

Re (in addition we will remember to turn off the shore mains supply should we be in a caravan park and go away from the caravan.
We only use the Pump and Tank (3), 24/7at CP’s, fill up when necessary.

(Carry a length of Black JG Hose and various joiners etc)

But each to his own….
AnswerID: 649232

Follow Up By: Member - McLaren3030 - Friday, May 15, 2026 at 08:49

Friday, May 15, 2026 at 08:49
Hi PerterInSa,

What benefit do you think turning the “shore power off” when away from the van is going to have? If anything, it could see your batteries not being charged. The water pump in your van is powered by the vans internal 12 volt system. When you store your van after a trip, is it connected to a 240 volt external mains supply?

Macca.
Macca.

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Follow Up By: Peter_n_Margaret - Friday, May 15, 2026 at 09:22

Friday, May 15, 2026 at 09:22
Unless parked up and not using the vehicle, we never turn the water pumps off.
At night there is a requirement for water at the toilet and hand basin.
While travelling it provides water for putting out fires. We have an outside tap with QC and a nearby hose. Water is the only way to put out spinifex fires.
It does create a risk in the event of a hose break while driving, but we do have multiple tanks.

If night-time pump chirping is an issue, then my habit is to fix the problem, not camouflage it.
Our pumps are mounted outside and are very quiet, so the bigger risk is when a tank is empty and a pump runs continuously and is not noticed. I have overcome that by having a LED come on next to the sink to show that a pump is running.

The new build will have the water switch in a more easily accessible location for night isolation, but the travelling isolation would require a 2 way switch..... Easily done, but need to think about that one.
Cheers,
Peter
OKA196 motorhome
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Follow Up By: Allan B (Sunshine Coast) - Friday, May 15, 2026 at 09:35

Friday, May 15, 2026 at 09:35
.
Hi Peter,
My habit has been to leave the water pump on at all times except during storage. recent events have caused me to reconsider that.
1) Several weeks ago the poly line from the water mains to our house meter ruptured but was quickly noticed and caused no damage other than a crater in the garden until the water supply authority repaired it.
2) More recently we returned from a week away from home to find water on the kitchen floor. A braided hose to the sink mixer had a pinhole leak. Luckily, it was limited flow and appeared to have occurred shortly before our return and no permanent damage occurred. But it may have been a different story if our holiday had been for a longer period.
3) Several months ago a couple of our friends came home from an extended vacation to find their entire home flooded. A water connection within the kitchen cabinet had incurred a major rupture. Extensive structural damage had occurred. They needed to evacuate their home for months and now it has been found so substantial that the insurers are considering demolishing the house.
4) Some years ago my sister incurred significant house damage due to a water leakage in the ceiling during their absence. It was an interesting fault but I won't detail it here.

So I have now resolved to turn off the van pump when vacating. There is an accessible switch that isolates the pump and the supply to the LPG HWS. Incidentally, that switch was provided in order to be able to isolate the pump in the event of an exhausted water supply as the pump would continue to run continually. Shutting off the LPG may also be considered but not quite a simple as flicking a switch at the exit door.

And in the home, I think that I will turn off the water at the meter whenever we leave for more than a couple of days. The electrical power needs to remain on for refrigeration but is less risk due to the RCD protection.
Cheers
Allan

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