New basin waste - won't drain once trap fills

[avonmouth]

I had a basin yesterday that took ages to drain.The slot was covered with silicone.

 

[dilalio]

I had a basin yesterday that took ages to drain.The slot was covered with silicone.

That's why I don't like the use of it for basin wastes.

 

[Elkato531]

If you pour water directly into the waste pipe does it flow away?
Has the waste pipe dropped at all? Sounds to me like there is a double trap situation going on where water is trapped further down the pipe.

 

[richw]

Funnily enough, I did think that maybe I'd obscured the slot (my first attempt I didn't realise the slot was a thing - I've not done a basin before!) but part of my second attempt was checking it was all clear and lined up correctly. I'd had the idea that if the overflow couldn't allow air in, then it would perhaps make a vacuum, which would stop it draining.

I am not sure about the pipework which leads to the drain. It's a 1930s semi, where the WC and bathroom were combined almost 20 years ago so much was altered. I don't know if it goes into the soil stack or via a hopper. The waste pipework under the basin (in a vanity cabinet, of course!) is solvent-welded... there's a 90, it goes down, but I don't know where, nor how it related to the bath or shower waste, as it's the opposite corner of the room.

I think I'll have to try pouring water directly into the drain (tricky without making a mess!). Then try with both traps (minus basin). Also test the traps just by filling via the bath tap (again). Hopefully that shed some light.

I'll get a couple of basin mates and maybe see if I can get some spare washers too.

 

[Alec_t]

Did you try removing the trap base and checking if the adjustable pipe blocks the exit?

 

[richw]

Not yet - I'nn going to head over soon. I already went to TS and got a couple of basin mates, just so I can avoid faffing about with maite or silicone. Annoyingly, I forgot to get some solvent weld pipe and fittings, as I may have to break that apart to inspect/clean. Why is it always the way that I forget something?!?!

I did my new kitchen plumbing a year ago, so thought a bathroom basin would be a doddle. How wrong I was.

 

[richw]

I am on site. The drain pipework looks ok, and I tried sticking a bottle brush in. I connected the trap directly to it, no basin waste involved, and once the trap fills, it doesn't drain away. The same with the old bottle trap.

I am starting to think there is a blockage, but how can this have happened at the exact moment I started messing about??

 

[richw]

I have given up. I put a hose down the drain and slowly poured water down. No problem.

Connect up either bottle trap and stick plenty of water down, and it just fails to flow.

If I hold the bottle traps under the bath tap, they both fill and flow out as expected.

Unfortunately, the in laws now have the prospect of trying to engage a plumber after someone else has had a go.