Washing machine drain pipe issues - rotten egg smell

DQY

Hi all,
Have been suffering from a sulphurous smell in my laundry for a while. Tried all the obvious things - cleaned the drum (smells fine), seal, detergent drawer, ran hot washes, used vinegar and bicarb etc. Figured it must be the drainpipe - detached it today and out came sulphurous smelling water, so going to give that a clean and see how it goes. However, wondering if the plumbing set up is contributing to the problem and whether we need to make some changes there to prevent getting this again. There is no standpipe - instead it attaches to the U-bend under the sink. There isn't a great deal of height between the trap and the connection that the washing machine drainpipe goes into and wondering if that's the issue, though not sure there's an easy fix.
Photo attached - washing machine drainpipe attaches to the left hand side connector (currently blocked with red rag), at the same angle as the dishwasher drain pipe on the other side.
Thanks!
DQY

FreeBear

Is there a non-return valve in the washing machine hose ?

It is often just a flap of rubber where it connects to the downpipe under the sink - If there isn't one, dirty water from the sink could be getting in to the WM hose and quietly festering. Rerouting the WM hose so that it is clipped above the sink connection might help to reduce any water flowing back from the sink.

DQY

Thank you @FreeBear! It doesn't seem to have a non-return valve - is that something you can add or would I need to get a new hose? Am soaking the hose overnight with boiling water mixed with bicarb of soda and will drag a cloth on a wire through it tomorrow. Any other tips on banishing the sulphur? (!)
Thanks!

Skint_yet_Again

I have this problem too. Dishwasher connection one side, WM other side. When the washing machine empties a sulphurous smell comes out of the plug hole. Sometimes I go to put washing in the machine & there is water in the drum (from the sink / dishwasher?)

Sorry being thick & not very diy female how do I reroute the WM hose above the sink connection ?

notbritishgas

When the fitter installed our new dishwasher he said the drain hose should be looped up before it connects to the drain, ie go up higher then loop down to the connection.
This prevents any water draining back into the machine.
In the OP’s case the dishwasher hose goes straight down and perhaps so does the washing machine when connected.

Skint_yet_Again

Ah that makes sense I will try that

Nearlyold

The spigots (which the drain hose attaches to) on the sink waste downpipe should be pointing UP not down - otherwise if the U bend is not fully clear and backs up a little you are more likely to get waste water from the sink entering the drain hose as well as back flow from the drain hose itself. PS have the you checked the U bend for blockages?) 

Homer_home

Both your dishwasher and washing machines hoses are routed wrong

Both hoses should form an upside down u when connected to the drain , this is so symphonic action is created when the washing machine is emptying and all the waste water is removed from the machine , with your current setup as soon as the drain pump stops running all the water left in the waste hose flows back into the washing machine and sits in the bottom of your washer getting stagnant hence the smell 

DQY

Thank you all!
@Homer_home - yes, we thought that looked wrong. By twisting the spigots so they point up (not down), as @Nearlyold suggests, does that achieve what we need?
We've now cleaned out the drain pipe, but assume that the inside of the machine (the bit where the pipe connects to it) is also dirty. I'd already run hot washes using washing machine cleaner. Is there an issue if I pour some of the washing machine cleaner fluid (Dettol machine cleaner, diluted) down the back of the machine where the drain pipe exits? 
Thank you!
DQY

Nearlyold

Do NOT pour any liquid anywhere over the machine. The smell comes from inside the machine. 
If your machine has an emergency drain hose - usually a flexi rubber pipe with a stopper behind the flap that gives access to the drain filter then use that to drain the last of the water still in the machine plus remove, clean and refit the filter whilst you're there. PS don't perform either of these things before the washing machine pump has finished emptying the machine!

DQY

Don't worry - not over the machine! Into the machine where the waste pipe connects - that is, the same place the water comes out. I've already cleaned the filter and drained out there (with machine off etc. obviously) - but wondering whether the bacteria that had clearly grown in the pipe are also in the insides of the machine: and so far, running cleaning washes doesn't seem to have addressed that (and drum smells fine) - so wondering whether more targeted action is needed to clean the bit between the drum and the waste pipe, if that makes any sense!