Help with Dishwasher & Washing Machine issue (maybe plumbing related)

[PiHigh]

A while back we moved the tumble dryer into the conservatory to allow us to have a dishwasher installed. Because of the dishwasher connections we had to move the washer to where the tumble dryer previously was. Set up is now as follows

Sink with cupboard underneath, dishwasher, narrow cupboard, washing machine

We had no problems with this when we had a Hotpoint but it reached the end of its life and Dh insisted on a Bosch. Since then every few months the washer tells me it has too much soap in and to fix it (after checking the filter is clear) I have to disconnect a piece of pipe under the sink and pull out loads of gunk (it seems like it's fibres from clothes, hair and soapy muck that hasn't been able to pass through this particular bit of pipe). I'm wondering whether the distance from washing machine to pipework under sink is just too far for it to handle and if there's any other option.

So, do you have a dishwasher and washing machine and do they both drain under the sink?

So, do you have a dishwasher and washing machine and do they both drain under the sink?

Yes.

What angle is the pipe that you find muck in, from where it leaves the machine to where it enters the drain?

It could be siphoning back when the dishwasher is emptying (happy to be corrected by Pigletjohn btw!) Have you tried pushing the pipe up so it goes up and then down before the connection to the gubbins under the sink?

The pipe is at an angle so that the grey outlet pipe from the washer is above it iykwim. There is some sort of washer or valve inside it and the muck seems to get through that but then not get down the next section of pipe even though the next section is bigger

the flexi waste pipe must rise up in a loop, where the top of the loop is higher than the water level in the sink, and higher than the waste pipe it joins. This should be as close as you can manage to the appliance. You may be able to hook it to the underside of the worktop with a piece of string something durable

It is preferable to run the waste hose into a stand pipe rather than a sink waste spigot or a Y connector, since dirty water cannot then run back towards the appliance, even if it is being forcefully pumped out of another nearby appliance.

One of these attached to the wastepipe is better than one of these attached to the sink.

Hmm, the piping is definitely more like the second of those links.

The waste pipe does go up behind the appliances at some point. I know that because it's a pita when you want to pull the washer out (we have to move the dishwasher out first and unhook it to give it enough length)

I suppose you could pull the plastic spigot out of the waste pipe and verify that it has been cut smoothly with no snaggy ends, and is cut to the largest bore that will tightly fit the hose. Smooth off the edges with sandpaper. The spigot must point upwards from the trap so the water flows down from the hose

But a stand pipe will be better. You may need a plumber but it is not complicated. Cutting and joining pipes needs a bit of practice.