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Flexi hoses have been an innovation that has certainly made life easier for plumbers and possibly even reduced costs for customers. However, they have also become a leading cause of flooded properties due to a plumbing system failure.
While the exact cost of flexi hose failures to homeowners and insurers is unclear, my personal experience replacing numerous burst hoses over the years and witnessing the major damage caused to homes, suggests that repair costs could amount to many billions of dollars.
This picture shows a burst flexi hose caused by corrosion of the stainless steel shield. Other than the obvious point of failure, you can also see the other issues on the hoses which may have eventually also caused a critical failure. (photo by Mount Coolum Plumbing)
While claiming to be stainless-steel the outer braided shield of these hoses can still corrode and rust, causing the tiny metal strands to break and fray.
When this happens, the water pressure from inside the hose causes it to expand and push out through the broken shield, where it can split and burst or be punctured by the sharp ends of the metal strands.
A major cause of corrosion of flexible hoses is fumes from chemicals, such as household cleaners, which people store in their cabinets.
When these fumes are trapped in the enclosed cupboard space under a sink or vanity basin it creates a corrosive environment which can cause a reaction with the stainless steel.
Using chemical cleaners on and around the hoses can also cause corrosion. This situation would be more likely to happen on an exposed flexi hose, such as the water inlet to a toilet cistern, where during the cleaning of the toilet, chemicals would be sprayed directly onto the hose.
Corrosion of the stainless steel could possibly also result from constant moisture over a very long period of time, due to leaks from or around the tapware above.
While stainless steel shouldn't corrode purely from water and moisture, the stainless steel used on some hoses may not be of the highest quality.
This a photo of some flexi hoses that were badly corroded due to chemical fumes. This was just a discovery during a standard mixer replacement and wasn't the reason for the replacement as the owner had no idea about the condition of the hoses. (photo by Mount Coolum Plumbing)
There are also other possible causes of failure, which could lead to a burst flexi hose, such as:
Physical damage from kinking, twisting or stretching of the hose, usually caused during installation by an inexperienced or unqualified person.
While the hoses are 'flexible', care must still be taken during installation to not damage the hose. This is where an experienced plumber is important, as they will know the safe limits of the hose's flexibility and bend radius.
It is very common to come across situations where the hoses may be slightly too short, or they can't reach the water inlet on a smooth arc without kinking the hose.
In these cases, a plumber will easily be able to carry out any required adjustments to the existing plumbing, including the supply of any extra fittings or pipework needed. Where someone without the materials, tools and skills required, could be forced to just 'make it work' and this is a where damage to the hose is caused .
Signs of an incorrect installation can also be used by insurance companies to deny claims of water damage caused by flexi hose failures, which is why a licensed plumber should always be used.
This photo shows a very badly installed flexible hose. It is very important that the hoses are installed without kinks or twists. (photo by Mount Coolum Plumbing)
Extremely high water pressure can cause stress to the flexible hose.
While flexible hoses should have a max pressure exceeding the pressures available at most residential properties, it is always recommended (and sometimes required) that residential properties are limited to 500Kpa using a Pressure Reduction Valve at or near the water meter.
But even if the incoming water pressure is well below the hose’s maximum rating, the hot water line can still develop static pressure far exceeding this level.
This is because during the heating cycle of the hot water system, the static pressure in the tank builds up and can reach very high levels, which is then transferred to all hot water pipework throughout the home.
While I've never personally seen a flexi hose burst from excess water pressure alone (there is always signs of corrosion), high water pressure definitely plays a part in expanding the internal hose and forcing it out of the corroded outer shield.
This is what a Pressure Reduction Valve may look like. These valves should be installed somewhere in the main water line, before it enters the house. They can be adjusted to reduce the pressure to a maximum of 500 kPa protecting the plumbing system and fixtures.
Due to the plastic or rubber internal core, flexible hoses will have a maximum temperature rating.
In most cases, this temperature rating would exceed temperatures available in most residential properties.
The exeption to this is for homes with roof mounted Solar Hot Water systems, which have an uncontrolled heating source (the sun).
In these cases, the temperature can reach extreme levels, which is why a Tempering Valve is always recommended (and required in new installations), not only to protect your plumbing fixtures, but also to protect people from severe hot water scalding.
This is an on-roof solar hot water system. Unlike all other hot water system types, the water temperature in an on-roof solar system isn't limited by a thermostat or a controller, which means the temperature can reach extreme levels (up to 99 degrees celsius).
The vast majority of burst flexi hoses are from the older style black rubber hoses which were in all of the earlier produced hoses.
This soft material can easily expand from water pressure when it is not completely contained within the braided shield causing it to burst or be penetrated by the sharp broken stainless steel wires from the rusted outer shield.
This material is still used in some flexible hoses on the market and although they may be more flexible due to the softer material, the greatly increased possibility of a burst hose far outweighs this slight advantage.
The risk of burst flexible hoses improved drastically with the introduction of an inner PEX core.
This material is far harder than the black rubber EPDM hose, which means less expansion under pressure and at the same time also harder to be pierced by any broken stainless steel wires.
But the issue wasn’t solved completely due to the ongoing corrosion risk of the stainless steel outer shield.
I have personally seen a burst flexi hose with a PEX inner core, so while the chances of a failure have certainly decreased with this newer material, it hasn't been totally eliminated.
This is why a visual inspection for any sign of corrosion or damage is very important and can help eliminate the immediate risk of a burst hose.
Over recent years, the introduction of corrosion-free Polyamide outer shields has totally changed the game when it comes to flexible hoses, where in conjuction with a PEX inner core, the risk of these hoses bursting is now extremely low if installed correctly.
Here is a definition of Polyamide from Corrosianpedia
"A polyamide is a curing agent chain of polymers linked molecularly by a -COHN- amine group. It is a key chemical component of corrosion coatings. Polyamide resins are resistant to acidic and alkaline substances that are the primary sources of metallic corrosion-inducing attacks."
Polyamide flexible hoses are becoming more popular and are available from many different brands and distributors, so in my opinion there's no reason for plumbers not to be using them in nearly all situations.
My first introduction to Polyamide hoses came a number of years ago, where they were displayed on the front counter of a plumbing supplier and I immediately recognised how they solved a major issue I was seeing more and more regularly.
These particular hoses were called High Class Hookers from Abey and I still use these exact hoses to this day!
This is an image of the High Class Hooker polyamide flexible hose with details of its features.
While standard flexi hoses, such as those used to connect the water to a toilet cistern are becoming more readily available, they are still not as common to be supplied standard with new flickmixers.
One particular brand of tap that comes standard with Polyamide flexible hoses is Ram Tapware
Ram made the change to these hoses many years ago now and they are supplied with all of their mixer taps.
There are other tapware brands that also supply Polyamide hoses with their flickmixers and I believe this is a very important deciding factor when looking to install a new mixer tap in your home.
Please ask your plumber who is supplying the tap or the store you are purchasing from about this before making a decision.
This is an image from a job where I replaced a basin mixer which had a burst hose, with a new Ram mixer. (photo by Mount Coolum Plumbing)
As you can see, the Ram mixer comes standard with Polyamide flexible hoses.
This is also a good visual comparison to show how the different outer shields look side by side.
There is now another option on the market that eliminates the risk of a burst flexi hose completely.
This option uses soft (hand bendable) copper pipes, to replace the flexible hoses that are sold standard with all flickmixers.
While copper tails were the standard when Flickmixers first came into the market, they haven't been available for many years.
This was until recently when the Australian company No Blows. started manufacturing and selling their product.
These copper tails have some advantages over all other flexible hoses, even the high quality Polyamide hoses, but they also have some disadvantages as well.
I can seen a reference to chrome plated copper tails on the No Blows website, but I can’t see these as being available for purchase at this stage.
But if they were available, I would then add an extra advantage as being they could look cosmetically better in some scenarios where the mixer tails were visible, such as on a wall mounted basin.
This may not always be the case, but some sink / basin / laundry cabinets and the water supply outlets are very hard to access, so flexible hoses would be far easier in many cases.
This is an image of the No Blows copper flickmixer tails. (photo from https://noblows.com.au)
Installing and replacing flexi hoses and mixer taps is licensed plumbing work and should always be done by a plumber.
This means that you will be covered by insurance (both yours and the plumbers) in case there is an issue, as well as be covered by any manufacturer warranties.
But you can do the most important part yourself, which is the visual inspection!
A regular visual inspection of the flexi hoses is the best way to prevent a failure of the hose and a flooded house.
This is also quite easy to do, as long as you are agile enough to get under the sink or basin to do this inspection.
Using a small torch or your mobile phone, try and position yourself under the sink, vanity basin and laundry tub so that you can clearly see the complete condition of the flexi hoses.
Sometimes this can be very difficult due to the size of the cabinets and shelving, so you may need to use your phone to try and take photos or video.
What you are hoping to see is some nice shiny stainless steel hoses (or even better, the dull grey polyamide hoses) with no rust whatsoever.
One other thing you can do, especially if you aren't able to do a thorough visual inspection, is to use your hand to feel the hoses.
It's very important to do this gently, because if there are any rusted or broken stainless steel braids, they can be very sharp and can easily pierce your finger, so please be careful when doing this.
Any rough surface on the hose that feels different to the rest of the hose is most likely a sign of corrosion and in which case a visual inspection may be necessary to see the full extent of the issue.
If you see or feel any sign of rust or corrosion, then you should think about calling your plumber to inspect and replace the hoses as needed.
While small signs of rust don't necessarily mean there is an imminent danger of a burst flexi hose, any type of rust is not ideal and shows the signs of a corrosive environment.
This means you need to be aware of a possible issue in the future and either have the flexi hoses replaced immediately (recommended) or just make sure to remember to keep an eye on them at regular intervals.
Thank you for reading this article, I hope it was informative!
For homeowners in the Mount Coolum Plumbing service area please contact me anytime to organise your completely free and no obligation visual inspection of all the flexi hoses in your home!
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