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Slow draining sinks and issue with washing machine drainage

Discussion in 'Plumbing and Central Heating' started by Fletcher123, 31 Jan 2015.

  1. Fletcher123


    31 Jan 2015
    Thanks Received:
    United Kingdom
    Hi all, could use some help. New poster.

    I live in a small flat on the 2nd floor. I first noticed a problem when I smelt dirty water coming from the bathroom sink. I wasn't sure what it was, but a few days later the washing machine outlet pipe backed up and caused some flooding to the kitchen floor.

    I did the normal layman tricks of trying Mr Muscle and the old wives tale of white vinegar with baking soda but it didn't achieve much.

    Afterwards, the kitchen sink started to drain slowly.

    To give an insight into the system, the further drainage is the kitchen sink, which links to the washing machine discharge pipe. This all goes into the same pipe through the wall to the bathroom sink discharge. This is on the opposite side of the wall so we are talking a few inches between the two.

    The bathroom sink then links down the side of the bath panels into the bath plughole. This then goes to the drainage which is boxed in behind the toilet and presumably close to the soil stack for the toilet.

    My problem is that the bathroom sink is boxed in so I will need to have a plumber take a look at this and do some sawing into it.

    Inevitably I will need a plumber to look at this. I wanted to check a couple of things with you guys before I give him a call so I don't look like an idiot. I have attached some labelled photos to help you out.

    (1) Does the plastic pipework under my sink look ok? There seems to be an extra and potentially unnecessary bend. Your thoughts would be appreciated. I am not against having the pipework changed.
    (2) I presume I have a blockage somewhere in the system. I am guessing it is the bathroom sink How much do you think it would cost to have a guy in Bristol to take a look at the system and work his magic?

    Many thanks.

  2. Well that's an entertaining use of a bottle and S trap!

    The lower trap isn't necessary - I suspect it's been used because there's a spigot connection for the washing machine waste.

    Easiest solution would be to remove the bottle trap, move the S strap up to the sink waste and reconnect the pipework.

    As far as clearing the blockage - most effective solution would be a Rotaworm in through the pipework below the sink.

    By the way, the AAV (the grey device on the top of the pipe to the right of the sink waste) is very low. Ideally it needs to be above the overspill level (rim of the sink) by 300mm. If it can't be raised that high then at least have it raised to the underside of the worktop.

    In terms of price can't really comment but there's less than an hours work to sort that lot out.
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  4. Also, from those pics, the main 40mm waste looks a bit too level to me. It could do with dropping down at the wall end to give a better drain off. If water is slow draining, the pipe gets gunged up and can cause rotten smells.
  5. bathjobby


    6 Oct 2004
    Thanks Received:
    United Kingdom
    I agree with all of the other suggestions, plus, it may just be a venting problem too. A quick easy test is to temporarily remove the AAV and try again taking care not to have water pour out the top of the pipe where you removed the AAV, as newboy said, its very low. But if it drains away quickly, it could be the AAV not working properly.
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  7. Madrab


    4 Oct 2012
    Thanks Received:
    East Renfrewshire
    United Kingdom
    You can check the main run for blockages - If you can fill that right hand pipe, by using a jug of water to pour water in then the restriction is in the main horizontal run, if you can't overflow it then then the blockage is in the pipework from the sink to the main waste pipe.

    Whilst I agree with all the advice from the guys above, I would be really tempted to remodel that setup.
    Where the bottom pipe T's into the 50mm horizontal run (is it 50mm as the bottom adapter suggests it?), I'd cut the main pipe there and realign the whole setup above it.

    Are you using the washing machine spigot under the sink, as pic1 shows the WM connection further down the run. There is a grey pipe running to the spigot under the sink too, is it a DW? If you are using that spigot then using the S Trap from the sink, run down to the spigot, then add an in-line anti-vac, then down to a 90deg bend into main horizontal run & put a pipe clip just after the bend to lift the horizontal run under the sink by a cple of cm's to give it a suitable fall. If not using that spigot then use the bottle trap and just add in the anti-vac and remove the spigot and then down to the elbow etc.

    The riser on the right looks like it's been a hangover from something else and someone's popped a push fit AAV onto it. Can't see why someone created that just as a vent, but hey, you never know... seen stranger :p Not required tho IMO if you add an anti vac.

    Oh and BTW, the WM's solvent welded swept T (pic1) needs to be replaced, it's on the wrong way, it's running against the flow, never good when the washing machine's pumping and the sinks draining :eek: Bit of a contraflow there!!

    Time to have it redone methinks
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