Smell from Washing Machine/Cap Spigot

jroy_998 · 2 Sep 2025

We've recently moved house and upon fitting the washing machine, I've noticed an eggy small coming from the drains when the washing machine does it's pre- wash drain.

After messing about with the pipework, I think I've narrowed it down to the fact that it's fitted to the horizontal spigot (the one at the back of the pipework). When the drainage hose is not connected and the tap is run, water will pour through the Spigot, so I suspect that the waste water is collecting in the pipe and when the drain kicks in, it releases all of the water that's been sat there for days getting smelly.

I could connect it to the other spigot (capped off with brown tape), but then that leaves me with the problem of an open spigot which pours water out every time I run the tap.

I've tried looking for something to cap it off should I remove the Spigot, but I can't seem to find anything. I have seen little cap for the spigot itself, but wasn't sure if this would be suitable given it's going to always have water coming up against it.

Is anyone aware of anything that would do this job, or am I better off getting rid of it altogether and fitting something like this instead - https://www.screwfix.com/p/mcalpine-adjustable-inlet-tubular-p-trap-white-40mm/46577 ?

Side question, why would one these horizontal spigots be needed if they're always going to expel waste water? Genuinely curious.

Thanks in advance!

Wayners · 2 Sep 2025

Run a cleaning program on machine which involves using white vinegar or cheap bleach or cleaning solution in drum then holding down buttons on ours to trigger the cycle.
Look in manual.
This runs hot water killing bacteria.
Use washing powder as the liquid is terrible for causing sludge and smells along with calgon which we buy off Amazon.
Calgon stops the bacteria and sludge

jroy_998 · 2 Sep 2025

Have tried all that, multiple times. It's still there. If it's run once a day it seems fine. It's when it's left for a couple of days that it happens.

I'm pretty sure the issue is the water from the sink backing up in the waste pipe, due to the water escaping from the spigot. Which is why I want to try the upper spigot and cap this one off.

accelerator · 2 Sep 2025

I'm not an expert here but some thoughts:

- Is there a blockage/restriction in your waste pipe (large grey pipe), that is making water back up? Would using some drain cleaner be worthwhile?

- What currently happens if you take the brown tape off the top spigot and run the tap? Does water come out? If the drainage was working correctly, I don't think that water should be able to escape from here.

RrogerD · 2 Sep 2025

You can buy the correct caps for the spigots from Screwfix etc. I'm not going to suggest something as I don't know exactly your setup. I wouldn't trust brown tape.

endecotp · 2 Sep 2025

jroy_998 said:
it's fitted to the horizontal spigot (the one at the back of the pipework).

You mean the one that is barely visible in your photo?

I have the impression that the washing machine outlet hose is coming up from the bottom of the cupboard to connect to it. Is that right? Please post a better picture where we can actually see that pipe.

The hose really needs to rise to just below the work top level, and then go back down to connect to the pipework. If it doesn’t, the washing machine will fill with sink waste water.

Madrab · 2 Sep 2025

Unfortunately, whoever plumbed that in didn't do it correctly. That spigot adapter should not be in that position on that design of the sink waste/trap run, it is actually in the section that forms part of the trap seal, that should just be a straight piece of pipe.

That all needs re-jigged, that spigot adapter removed and then use the spigot that's higher up.

As suggested too, the drain hose should be up and over and not run under the units, that's a typical kitchen fitter's mistake.

Hugh Jaleak · 2 Sep 2025

As above, if replacing the Tee section is a problem, then you should be able to remove the spigot from the Tee, and fit a 40mm cap in there instead to seal that off.

Drain hose then needs rerouting so it rises from the machine, as high as possible underneath the Worktop then drops to the discharge point. This prevents dirty water from the sink draining back into the machine, which is the likely cause of your issue.

jroy_998 · 3 Sep 2025

Thanks all.

The plan was always to attach it to the spigot higher up, it just left me with the lower one that leaked water which will need sorting.I can re-route the waste pipe higher up whilst I'm messing about down there too.

Is it a case of getting rid of the lower tee and replacing it with something like this (once measured) - https://www.wickes.co.uk/McAlpine-T28M-White-Multifit-Straight-Pipe-Connector---38mm/p/227098 .

Or even getting rid of that and the trap and replacing with this - https://www.wickes.co.uk/McAlpine-ASA10-White-Adjustable-P-Trap---32mm/p/227022 (being adjustable might make things easier?).

jroy_998 · 3 Sep 2025

endecotp said:
You mean the one that is barely visible in your photo?

I have the impression that the washing machine outlet hose is coming up from the bottom of the cupboard to connect to it. Is that right? Please post a better picture where we can actually see that pipe.

The hose really needs to rise to just below the work top level, and then go back down to connect to the pipework. If it doesn’t, the washing machine will fill with sink waste water.

Yep, that's the one. I did try but getting my hand/phone in there and at the right angle was somewhat difficult. I thought an additional explanation would cut it.

You're right though it is coming up from the bottom of the cupboard so will need moving. Still have the problem of water coming out of the bottom spigot too.

Madrab · 3 Sep 2025

Actually, looking at it again, that is an appliance trap that McAlpine supply, with the appliance spigot at that level but it doesn't come as part of a sink kit setup, I think that's been added. The main problem though could be with the level of that horizontal section of grey waste heading out to the right, ideally the waste pipe would be heading downwards and out or at least downwards. I know the camera angle can be deceiving sometimes but is that section of pipe level or even uphill?

Taking that section out though and replacing with an adjustable P trap may do the trick but again I'd be wary about how good a fall there is on that grey waste pipe

jroy_998 · 5 Sep 2025

Hopefully these should be a bit clearer?

Having had a look at it, it definitely seems like the grey pipe is at best straight, rather than angling away.

Hopefully getting rid of the extra section, putting an adjustable P trap on it and using that to lift it up a bit should sort it?

Thanks again.

Madrab · 5 Sep 2025

Yes - you just want it angled down slightly so the water will always want to flow out, it'll help with drainage and help to keep the pipework cleaner.

endecotp · 5 Sep 2025

jroy_998 said:
Hopefully getting rid of the extra section, putting an adjustable P trap on it and using that to lift it up a bit should sort it?

No, the most important thing is to have the washing machine outlet host rise up as far as possible, ideally to immediately below the worktop, and then back down to the trap. Currently it rises from floor level and into the trap. Half pf your sink waste water will be draining into your washing machine.

While the grey pipe might not be ideal, this is surely a secondary prpblem.

jroy_998 · 5 Sep 2025

endecotp said:
No, the most important thing is to have the washing machine outlet host rise up as far as possible, ideally to immediately below the worktop, and then back down to the trap. Currently it rises from floor level and into the trap. Half pf your sink waste water will be draining into your washing machine.

While the grey pipe might not be ideal, this is surely a secondary prpblem.

I was only referring to the grey pipe problem there. I'm also aware of the importance of sorting the washing machine outlet. Numerous people have pointed it out and I have previously mentioned I will sort it whilst I'm down there.

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Smell from Washing Machine/Cap Spigot

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