Bath waste and basin waste

Discussion in 'Plumbers' Talk' started by Adam535, Aug 14, 2018.

  1. Adam535

    Adam535 Member

    Hi guys,

    I’ve just bought my own place, slowly getting round to fixing stuff. The water in the bath wasn’t going down, it was really slow in draining. Thinking it was a blockage I bought chemical unblockers without any luck.I picked up courage to open it up. No blockage but plumbing design issue I think

    This is what I have found:

    The bath and basin are connected to the same waste. See photos

    And when I put basin tap on makes a gurgling sound. And bath water is super slow in going

    https://photos.app.goo.gl/oyLc6pV4EzNcRUeT9

    https://photos.app.goo.gl/4jKFYV7JEcajgnneA

    https://photos.app.goo.gl/1LG5ibacxNEor3kp8

    https://photos.app.goo.gl/4cFLuKtq7aydGVyT7

    https://photos.app.goo.gl/yH2EMRGKcGrryfdp8

    Look forward to solution.
     
  2. rogerk101

    rogerk101 Screwfix Select

    From the photos you've posted, nothing is obviously incorrectly plumbed. depending on how far the run is from where the bath and basin wastes meet until the main soil stack, I might have inserted a 40mm air admittance valve somewhere along the run, but that would just stop the gurgling, not improve your blockage situation.
    Have you dismantled, cleared/inspected the traps both under the bath and the basin?
    Can you see where they join the main soil stack?
    Is there any service point along the way, through which you could poke a stiff wire?
    If not, your 3rd photo shows a grey compression coupler just before where the two drains meet. If you loosen the bath trap and then pull the bath waste away from the coupler, it should separate, allowing you to poke something all the way through to the stack if necessary.
    Good luck!
     
  3. Adam535

    Adam535 Member

    Thanks for reply roger.

    The water from sink is draining fine. Also I have checked the pipe from bath trap to where it joins, this is also clear. Bath trap is also clear. I am confused

    The bath waste pipe is 40mm which goes into a reducer 40mm to 32mm
     
  4. rogerk101

    rogerk101 Screwfix Select

    I'm thinking it's between where they join and the main soil stack; hence the need to find a way in with a poking wire.

    That's a shame ... to go from 40mm to 32mm is a seriously bad thing to do especially for a bath outlet ... but it's not a reason for a blockage, just a reason for slow emptying.
    If you can got to it, I would replace the 32mm piece so that it's 40mm all the way.
     
  5. Adam535

    Adam535 Member

    Ok just noticed when I put basin tap on 1st and keep it running. Then put on bath tap on . The bath empties at good rate
     
  6. Adam535

    Adam535 Member

    Anymore solutions?
     
  7. Adam535

    Adam535 Member

    Where would I put a anti vac?
     
  8. rogerk101

    rogerk101 Screwfix Select

    I would use a T right after the bath trap outlet and mount it up under the rear side of the bath. I'd use a compression T so that it can be positioned and serviced if necessary. The anti vac will have to be mounted higher than the fullest bath you're likely to have so that when the bath empties from being that full, and the water backs up because of the 32mm restriction further down the line, it won't be able to get to the anti vac.
    If the basin empties really fast, it won't suck the water out of the bath trap because the anti vac will be allowing air into the pipe via an easier path than the bath trap.
    The fact that you have effectively two 40mm wastes going into a 32 mm waste means that you're far more likely to get gurgling as the 32mm pipe will be so full that the waste water flowing through it WILL create a vacuum behind it.
     
  9. Adam535

    Adam535 Member

    Thanks roger, so I am thinking get a anti van trap for the basin. This is highest point.
     
  10. Adam535

    Adam535 Member

    Just a update:

    I’ve disconnected sink from the waste. Water flows perfect from bath

    Now I’ve connected a anti vac to sink. Back to same problem, but little better flow.

    Do you I need to add something more? To the pipework
     
  11. KIAB

    KIAB Super Member

    Have you cleaned out the basin waste outlet, a lot of crud can build up, especially if it is slotted & combines the basin overflow outlet, & restrict the flow.
     
  12. rogerk101

    rogerk101 Screwfix Select

    Which problem(s) remain?
    You say the bath empties out fine now. Does the basin empty fine now too?
     
  13. Adam535

    Adam535 Member


    I’ve cleaned it.
     
  14. Adam535

    Adam535 Member


    I’ve fitted anti vac to the basin. Basin empties perfect.

    Bath still same - water going very slow.

    lots gurgling when I put on basin tap and definitely something to do with air and vacuum.


    When I take off the cover for air on anti vac the bath empties perfect.

    Do I need to fit anti vac to bath too?

    Air inlet to the bath pipe?

    https://photos.app.goo.gl/2JLHKWp95bBMf85v9
     
  15. Adam535

    Adam535 Member

    Video might give better idea
     
  16. rogerk101

    rogerk101 Screwfix Select

    That's what I suggested in post #8. ;)
     
  17. Adam535

    Adam535 Member

    Ok I will try it
     
  18. Adam535

    Adam535 Member

    Ok I will try it
     
  19. kiaora

    kiaora Guest

    Hi
    I’m familiar with this particular problem,
    After the tee connection, my suspicion is the waste pipe is somehow forming another trap, this often happens when the pipe from the tee to soil pipe goes slightly uphill!
    If you have 2 traps in series it will perform like a partially blocked pipe, when in fact it’s not blocked at all.

    Have a close inspection of the pipe from tee to the discharge point/ soil stack

    Regards
    Peter
     
    retiredsparks likes this.
  20. Adam535

    Adam535 Member

    i thought i would update. thank you for everyone who replied.

    another air inlet valve was needed on the 40mm waste pipe from bath.

    ideally use a air inlet valve or quick temporary measure is put T-Fitting with a big pipe in the top the pipe needs to be higher that basin waste. this lets enough air in.

    i will take photo next time i'm there. in the future i will change all the pipes and plumb correctly.
     

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