1.5 bowl sink waste too low?

26 Jun 2021
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United Kingdom
We are in the process of installing a new kitchen, and we've hit a problem with the sink. Everything has been replaced, so it's new units & worktops with a 1.5 bowl ceramic top mount sink which has replaced a metal 1 bowl sink. We bought a new waste to fit the 1.5 bowl but when we fitted it today, it appears that the water doesn't drain away properly. When testing the drainage on the .5 bowl there is some water going outside, but the rest is rising up into the other sink. Is the waste trap too low & the waste pipe going outside too high? That would seem obvious, but just at a loss how to solve this without destroying more of the kitchen drilling new holes into brickwork, etc. Any advice would be appreciated as I'm aware that what we've done could be horrifically wrong! Photo attached of the set up. Thanks :)

Edit: I'm aware of physics needing the water to go down, BUT the old waste didn't flow down either, just slightly upwards. However, considering the ridiculous DIY fixes we are finding (bought last year & just a neverending bodge DIY nightmare that someone tried to cover up with mastic & gloss paint...) it just doesn't surprise me that what they did is probably not correct either!


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Yup, that'll never work. Ideally the outflow of the waste through the wall needs to be lower than the lowest point of the trap.
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Thank you both - we're just sorting out a core bit now and will have to dismantle the unit to get to the wall but it's do-able!
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Careful if you're coring through a wall, you need to use the correct type of drill - SDS with clutch.

The core will go through the unit and then the wall, you don't necessarily have to dismantle the unit as long as it's all long enough - dry corer and shank adapter together.
We've got an SDS with clutch so all okay on that front. We can take the thin back bit of the cupboard off as we can just pop it back in afterwards. It's going through 2 courses of brick so think we've got to go from both sides due to the length of the core bit (but we're just trying to sort that at the mo as we need to buy one).
I always core from both sides, otherwise you could get chunks of bricks falling as you go through.
I know some don't care because it's behind the cabinet, but i like to make good after passing the pipe so to avoid vermin access.

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