Can I replace a flexible drain hose with a solid one?

[Neville Hillyer]

I have moved house and traced a flood to several pinholes in a washing machine extended flexible drain hose. I assume they were caused by a mouse since there are droppings nearby.

I have no experience of washing machine hoses connected above sink traps but, apart from the leak, it appears to work well.

My research indicates that this is now very common and is clearly simpler and cheaper than a separate 40mm trap and should have a lower flood risk.

Can somebody tell me where this method is detailed in the UK Building Regulations and say why I can't find any information on an equivalent diameter fixed pipe solution?

Whilst I will probably still need a short length of flexible hose to remove the washing machine I would like to make it less attractive to mice. I can't see why solid pumped pipes should not be allowed to replace fragile flexible ones.

 

[WC1]

Its fine under regs, not sure where.
The "proper way" is separate trap.
You need quite a lot of flex to get the machine in and out easily.
Its rare that mices eat them and you'd be better to get rid of the mices than what you suggest.
Make sure you have a jubilee clip holding the outlet on to the spigot above the trap.

 

[Neville Hillyer]

Its fine under regs, not sure where.
The "proper way" is separate trap.
You need quite a lot of flex to get the machine in and out easily.
Its rare that mices eat them and you'd be better to get rid of the mices than what you suggest.
Make sure you have a jubilee clip holding the outlet on to the spigot above the trap.

Judging by the ultrasonic devices and neighbours remarks there is a long history of animal damage here. I am told squirrels destroy lead flashing.

I suspect the easiest fix would be a 20mm solid plastic pipe which could still be eaten but not as easily as the paper thin flexible drain pipes.

What are the various arguments for the height of a 20mm pipe connected above an existing sink trap? The original long flexible drain pipe ran along the floor where it remained full of water until most of it had leaked out of the mouse holes.

As a retired design engineer I am tempted to explore why washing machines fitted under worktops don't come with a totally non-flexible hose option - perhaps adjacent or under skirting removable links could be used - perhaps combined with 15mm copper for both supply and drain.

Has anybody come across such a solution?

Are there any suitable forums here to discuss such things?

If not can anybody recommend a suitable product design forum?

 

[Ric2013]

As a retired design engineer I am tempted to explore why washing machines fitted under worktops don't come with a totally non-flexible hose option - perhaps adjacent or under skirting removable links could be used - perhaps combined with 15mm copper for both supply and drain.

Machines tend to vibrate (when they do not actually move) in use, so TOTALLY non-flexible would not work by conventional methods, although the disc-braked Citroen 2CV did use a coil of solid (steel) brake pipework instead of a rubber section, so I suppose a workaround is technically possible.

Since the washing machine drain hose runs from the tub to the pump by gravity, the pump will always be at the base of the machine.

The reason flexible pipes are used is likely to be that the solution that tends to be adopted in consumer product design is not necessarily the technically superior one. If it were, no plumber would be using flexible tap connectors. With washing machines, flexible pipes are (normally) very reliable, can be installed without requiring high levels of skill, and, since most washing machines/kitchens do not last many years, the additional cost of employing skilled workers to install solid pipework would be a recurring expense that most people want to avoid.

 

[Neville Hillyer]

I am not sure which of my questions you were replying to but I am grateful for your vibration remark. If I don't use a short length of normal flexible pipe I may use the braided ones I am going to take off the kitchen taps.

My thoughts about height of drain pipes are that for both pumped and gravity and for all types of pipe it may be best to have a downward slope from the washing machine to the under sink trap. This should reduce flood damage caused by both pipe damage and clumsy washing machine removal.

 

[Ric2013]

I was replying to various points. I would, however comment that I have taken apart and repaired a number of washing machines and have not personally come across a leak from an outlet hose. Perhaps an alternative solution to your problem would be to wrap the outlet hose in something protective that mice dislike. I have heard (it may not be true) that traditional rough felt pipe lagging has the advantage (despite inferior thermal properties and higher cost) over foam lagging that mice dislike the felt and tend to leave it alone.

My thoughts about height of drain pipes are that for both pumped and gravity and for all types of pipe it may be best to have a downward slope from the washing machine to the under sink trap. This should reduce flood damage caused by both pipe damage and clumsy washing machine removal.

There is no harm in keeping the flexible tube at a high level (and thus empty) for the majority of its run.

It is, however, worth considering that most washing machines have a small sump of water that is intended to remain full in normal circumstances. Since most (but not all: I think Miele can be drained to a floor level gully) washing machine manufacturers require the installer to have the drain outlet at a high level (around 75cm above the base of the machine), this sump remains full because the machine can only evacuate water using the pump and not by gravity. The pump, incidentally, is centrifugal and will prefer pumping up.

You may find that if you merely drain to the floor level (i.e. down), the washing machine will be constantly draining and not be able to remain full when a wash cycle is in progress and there may be other issues if that sump is not kept full between cycles, such as the outlet seal float ball allowing dust and fibres from the wash to settle in the sump during a wash cycle and causing blockages.

On the Chesterton's fence principle, I would advise a bit of careful observation to try to understand what purpose the 'standard' arrangement serves before modifying it. Have you tried the Washerhelp forum? It is/was run by a washing machine service technician who may be able to comment further.

 

[SimonG]

Extend 40mm waste pipe and use an appliance trap.

 

[Neville Hillyer]

Extend 40mm waste pipe and use an appliance trap.

I could but a pumped closed pipe is:

1 - easier and cheaper to install
2 - odour free
3 - flood free

I would prefer answers to to my questions.

 

[SimonG]

I could but a pumped closed pipe is:

1 - easier and cheaper to install
2 - odour free
3 - flood free

I would prefer answers to to my questions.

It was an answer to your question.

As a professional I wouldn't recommend that you half arse a job like this. It will prove to be expensive, time consuming, very odorous and very wet.

This reminds me why I prefer to be in the plumbers arms.

 

[Neville Hillyer]

It was an answer to your question.

Which one?

 

[Chuck]

The section of the UK BR you are looking for is H-1:

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/442889/BR_PDF_AD_H_2015.pdf

I don't think that your proposal breaches UK BR but you should ensure that your arrangement complies with the washing machine manufacturer's installation instructions.

As a retired design engineer, it should be obvious to you that connecting a 75kg oscillating mass driven by a 1kW motor to relatively flimsy pipework via a rigid coupling is is a bad idea. This (vibration isolation) is the reason every connection to a washing is ca 1m long and floppy.

You seem to have got tunnel vision with this problem. Vermin inside your house chewing pipes is the problem you need to get solve by getting rid of the vermin. Even if you armour plate the drain hose the mice/squirrels/rats will just find something else to chew.