blocked bathroom basin

[thebishop]

I had a new basin fitted last year as well as part of a refurb. The waste pipe going to the main stack was also newly fitted as part of this work.

Drainage worked fine until just recently but then it started draining pretty slowly. I had a look at the pipework underneath but it was so flimsy that one of the joins came away in my hands.

So I called out the guys who installed and plumbed it in and they had a go at fixing it. However, although they refitted all the joins below the basin, the drainage actually got worse to the point where water is not flowing at all now! The guys said they would come back and check the waste pipe for blockages.

Before I call them back or get someone else to look at it, I wondered if anyone could see if the issue is their pipework rather than a blocked pipe. I've attached a picture...

Untitled

• thebishop
• 1 Apr 2015
• 1

I'm confused as to why there are two p-traps there instead of one.

Any thoughts?

 

[St0rmer66]

While it's unusual to have two traps like that (probably done for ease of install rather than for any benefit) I don't think that would cause the issue of no flow! It must be a blockage somewhere. Can you not just remove the traps yourself and look? The joints should undo easily by hand.

 

[thebishop]

Thx, I'll have a look on Friday. My main worry is that the waste pipe is hidden behind tiling and is at least a couple of meters long. Would you suggest using a wire hangar or something like that to poke around.

I was also considering using one shot drain cleaner (sulphuric acid) or caustic soda. Do you think this is worth trying? The drainage is extremely slow but does eventually seep through. It's something like 5 minutes for a less than quarter full basin to drain away. This makes me concerned that chemicals are more likely to damage the porcelain and the plastic pipes rather than fix the block.

 

[St0rmer66]

I would remove the traps before using any chemicals. Physically removing it is much better than dissolving it and more likely to get rid of EVERYTHING that's blocking the pipe.

If it turns out to be further along than the traps then the chemical solution might work as long as there is DEFINITELY some flow through it. I cannot stress enough that you need to be sure there is some flow. If the water isn't moving then you're just making the problem worse as you'll have corrosive chemicals sat in your sink/pipes which will be hard to remove when you eventually do have to take the pipes out!

 

[Newboy]

I was also considering using one shot drain cleaner (sulphuric acid) or caustic soda

Under no circumstances use OneShot or similar on internal pipework and under no no no no circumstances try caustic soda and OneShot either before or after each other.

With two traps it's possible you have effectively got an airlock - re-piping the waste properly would be a start

 

[thebishop]

Thanks for the advice.

I just checked that both traps are clean and clear. I couldn't get anywhere with a wire hanger. The waste pipe goes down vertically before turning off and I can't get further than that.

I'll get someone in to redo the pipes and check for blockages.

 

[St0rmer66]

I was also considering using one shot drain cleaner (sulphuric acid) or caustic soda

Under no circumstances use OneShot or similar on internal pipework and under no no no no circumstances try caustic soda and OneShot either before or after each other.

With two traps it's possible you have effectively got an airlock - re-piping the waste properly would be a start

I agree with your point about the chemicals, they are too easily available if you ask me. So easy to create a toxic mixture for anyone who doesn't realise what they're doing.

I do however doubt an airlock, if there was when the sink was only partly full then maybe... but a full sink of water would easily overcome those two traps and drain out. Bad practice to have two though for sure.

To OP: It may be possible to re-pipe with what you have there if you switch things around a bit. The bigger of the two traps near the wall is the one I'd use and get rid of the smaller one.

 

[Nige F]

Before I call them back or get someone else to look at it, I wondered if anyone could see if the issue is their pipework rather than a blocked pipe. I've attached a picture...

Untitled

• thebishop
• 1 Apr 2015
• 1

I'm confused as to why there are two p-traps there instead of one.

Any thoughts?

Good one for April 1st 2 traps FFS