Blocked Double / 1&1/2 sink water trap

1 Mar 2020
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United Kingdom
Hi all!
I've recently moved and the home I moved into has a kitchen sink with a 1&1/2 bowl kitchen sink.

I have a 1&1/2 kitchen sink bowl. The 1/2 sink waste is completely blocked and doesn't drain at all. The full sink bowl runs with no problem whatsoever.

I've removed all the pipes from under the 1/2 sink bowl and there is no blockage. Also, the 1/2 sink bowl connects into the waste pipe further down from the full sink bowl so the blockage cannot be anywhere else.

Everytime I remove the pipes, I empty the u bend then when I run the water into the 1/2 bowl, the water seems to fill the u bend and then stop moving.

Can anyone offer advice? Is this some kind of water pressure issue preventing water from pushing down the 1/2 sink waste?
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The full sink is on the left and the 1/2 sink on the right.
Empty both sinks and traps then remove the access point to the bottom left and clear from there.

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In fairness whoever installed that did a pretty good job in my book. I'd do as Andy has said, then poke a curtain wire or snake along the pipe from the 1/2 bowl end, until you see it emerge at the Tee. This will ascertain that section is clear.
Thanks Andy and Hugh, I will give this a go tomorrow.
I haven't ever removed that pipe access cover to the left, do they typically just screw off? It seems quite stiff and I wouldn't want to force it and break it!
Thanks, Dan
Have you tried just plunging with a sink plunger? If you’re not comfortable with the access cap, try removing the trap which the 1/2 bowl connects to and go from the wastepipe to elbow and down with a auger type drain snake.
Some hot water down the sink first may make it a little easier to undo, if you're still unsure, dont force it. To be honest, if you can get a snake along from the trap (offer it up externally first to gauge how far you need to go to get through to the tee), then that should prove the pipe is clear, (or at least has a hole big enough for the snake to go through), boiling water and soda crystals may then finish the job.

Avoid using chemicals, they can melt the pipework as well as any blockage, and if they dont clear it, they will also melt flesh and tissue of the poor sod who then has to take the pipework apart...
That leg of solvent-welded from the 1/2 sink is very near flat- good odds there's a blockage in there, people tend to chuck all sorts of odds and ends into the halfsink when they're washing up (coffee grounds, food scraps, that sort of thing). Treat as Hugh & Andy's posts
Thanks for all the tips guys. I have used a plunger yes, for a long time, and also tried soda crystals. Today I will proceed by:

1)Buying a drain snake.
2)Pushing it through the 1/2 sink plug hole and seeing how far it goes.
3)If that doesn't work, remove the access point and use the drain snake from there.

Will update tonight / tomorrow :)
If the 1/2 bowl trap is clear, and the full bowl drains without issue, the problem can only be in the run from the 1/2 bowl to the tee. Possibly full of FOG, (fat, oil or grease), in which case if you can make a hole through it with the snake, the hot water and soda trick down the 1/2 bowl should help remove the rest. Just make sure it doesn't congeal further down the system.....
Thanks for all your advice..
I used the drain snake on the pipework for the 1/2 sink starting further on down from the u bend... - definitely came across some fatberg type thing in the vertical pipe.
I seem to have dislodged that enough.
I then took off the access cap and ran the drain snake through there - seemed to find another blockage or fatberg type thing further down. I was a bit worried I pushed this down further rather than breaking it up.

I've run hot water and soda crystals down both sink holes and both are running fine. Hopefully this is resolved. Although, the 1/2 sink drains quickly, it gurgles at the end which might mean something is still blocked a little somewhere.

It seems fairly fixed though, can't thank you all enough! A £12 drain snake saved me the headache of arranging, being around for and paying a plumber.
Thanks for the feedback, glad we could help. Well done as well for being able to sort out, seen some plumbers run a mile because they don't want to get dirty or can't cope with the smell.

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