Washing machine drain fills sink, but drains if I move pipe

[Mottie]

Never seen anything like that before. Shouldn’t there be some kind of adaptor coming out of the floor with an air valve on it?

 

[paulhick]

Never seen anything like that before. Shouldn’t there be some kind of adaptor coming out of the floor with an air valve on it?

There is an air valve on top of a vertical pipe in the loft, that I think is on the top of the main vertical pipe that connects into somewhere. Not sure how it all connects though.

 

[CBW]

The valve in loft connects to the main drain and admits air in, these are known as an air admittance valve. Flush your toilet and see if water rises in bowl, that should give an indication if there's an issue with that.

Builder has rodded all external drains, need to check all internal where the kitchen sink and washing machine empty.

 

[paulhick]

The valve in loft connects to the main drain and admits air in, these are known as an air admittance valve. Flush your toilet and see if water rises in bowl, that should give an indication if there's an issue with that.

Builder has rodded all external drains, need to check all internal where the kitchen sink and washing machine empty.

Toilets seem ok at the moment, level is back to normal within a couple of seconds of flush at the moment, but before the builder rodded external drains we did have problems where water would sputter out of nearby shower or sink when toilet was flushed. This hasn't happened since drains rodded, but the washing machine problem has reoccurred since then.

For checking the internal bits, would something like this be suitable? https://www.screwfix.com/p/drain-unblocker-7-6m/11325

Wondering if the washing machine has coughed out some fluff that is stuck somewhere, all the problems in the house seem to start after the washing machine runs and the sink fills.

 

[CBW]

Wouldn't use the tool just yet. Firstly I'd be checking the trap for any partial blockage, then soda crystals and boiling water.

 

[foxhole]

If sink fills when wm empties they ubend is blocked

 

[Madrab]

First check the trap, if it's clear then get a cheap plung pump from TS, block up the overflow, disconnect the washing machine spigot off the trap and block that hole up and plunge the waste and see if that clears it.

 

[paulhick]

I've unscrewed the u bend and don't see any problem there. I've had a go with a "normal" plunger but will try again blocking off the washing machine and overflow. If I can get to it, is it worth trying to plung directly on the floor pipe hole?

Here is a video https://photos.app.goo.gl/uJfjXUnqM5ZPLhWm8 of what happens when I wiggle the pipe under the sink (sound recommended). Definitely think air pressure is building up somewhere, it drains really quickly once I open the system up. But I don't want it to be open all the time, because then smells can get in, right?

I've also attached a clearer picture of the arrangement of pipes under the sink.

 

[JimCrow]

The reducer in the soil pipe has been pushed too far down the pipe and looking at the video could be fouling a bend, disconnect the waste and pull the reducer back up to where it should be, refit the waste and try again, if you still have the problem then the drain is blocked.

 

[CBW]

What happens when you use the sink? Have you filled emptied and watched the rubber seal at the bottom? I agree with @JimCrow.

 

[paulhick]

The reducer in the soil pipe has been pushed too far down the pipe and looking at the video could be fouling a bend, disconnect the waste and pull the reducer back up to where it should be, refit the waste and try again, if you still have the problem then the drain is blocked.

If I understand you right I should slide the black rubber washer (is that the reducer?) up the white pipe so it sits on top of the wider outer pipe? Should the white pipe go through the middle of it, or rest on top?

I've attached a (hopefully) clearer picture of how it is now.

 

[CBW]

Can’t get a decent image for some reason, however this is what it will probably look like removed, the fins need to enter the 4” terracotta coloured pipe and sit flush, if you take it to the top of the white 4” it’ll probably be loose, looks like they’ve used the wrong fitting, pointless having the white 4” socket if using that?

https://www.screwfix.com/p/mcalpine...sAbn2qKyndY2PtZCtzM3IiGN1cPv5tlsaAkPHEALw_wcB

I’ve edited your photo to show where it should go to, but I’d personally either change it for a different connector or get the builder to do it.

 

[paulhick]

Can’t get a decent image for some reason, however this is what it will probably look like removed, the fins need to enter the 4” terracotta coloured pipe and sit flush, if you take it to the top of the white 4” it’ll probably be loose, looks like they’ve used the wrong fitting, pointless having the white 4” socket if using that?

https://www.screwfix.com/p/mcalpine...sAbn2qKyndY2PtZCtzM3IiGN1cPv5tlsaAkPHEALw_wcB

I’ve edited your photo to show where it should go to, but I’d personally either change it for a different connector or get the builder to do it.

That link is what it looked like. I've attached before/after photo of what it now looks like. The white pipe through the middle was very snug and it now sits fairly snugly inside the top of the wider pipe in the floor.

I think the root cause may be elsewhere, but will see if that has any affect.

Thanks to everyone who has suggested things to check, been really useful to have opinions for possible problems. Will be chasing up the developer on Monday and insisting they send someone to check everything over as it seems someone has done a bit of bodging somewhere during the build!

 

[Hugh Jaleak]

Dear god, what a mess, but sadly typical of rushed, bodged up building work that gets passed off these days.

First off, you have a problem somewhere. Golden rule is air behind water, what's happening is, an appliance discharges, the water cannot escape, (as the outgoing pipework is blocked down the line somewhere), so the volume of water is either displacing the air trapped behind the blockage via another outlet, or you are manually releasing it by wiggling that rubber connector.

If the builder is unable (or unwilling) to sort this out, engage a drainage contractor, (get a quote before committing to anything), and get the drain runs CCTV surveyed. Possible there's either a blockage, or a 'belly' (dip) in the pipe that's causing the issue.

Secondly, I'd replace that rubber connector with a rigid type, I dont like the use of the flexible connectors internally, possibility back pressure in the drain could displace it, and/or effluent escape into the room in extreme circumstances. That particular fitting you have Osma say is ok for internal use, but it should be fitted into a spigot end, not a socket, hence why it isn't very tight and could possibly cause issues.

 

[paulhick]

Just to add some (hopefully!) closure to this.

The developer initially tried to blame Thames Water's main sewer, but TW checked this and reported it fine (as I suspected it was). The drainage contractor was sent back to recheck all the drains under the house and since then everything seems to be ok. They aren't telling me what they actually did, but I suspect they don't want to admit to fixing a bodge or pulling a load of building rubbish out if the drains.

Thanks to everyone who contributed, was very useful to be able to sound like I know what I'm talking about when speaking to developers customer service department.