How to fix drainage smells from removed dishwasher?

[Mo8]

Hello

Prior to my moving in this new place, the previous owner removed the dishwasher.  On the wall behind where the dishwasher was is a white u-shaped plastic pipe that has a plastic cap on it with some dark blue 'ointment' around the cap fitting. 

When I wash up and empty the washing up water, the above plastic pipe gurgles and there is a horrible smell coming from it even though it has a top on.

The left hand sink plug hole (there's 2 small sinks side by side) also had the same horrible smell, so I poured Easy Off Drain clearer from Coles down it and the smell seems to have gone from the plug hole, but it is still coming from the above plastic pipe.

The other day, a small piece of mouldy tomato came up through the left hand sink plug hole.  It's not mine, as I clear my plates before washing them.  It's maybe the previous owner's piece of tomato.

Please advise.

Photos of plastic pipe to follow.

Thank you.

[MitchellMc]

Welcome to the Bunnings Workshop community @Mo8. It's sensational to have you join us, and many thanks for your question about sink wastes.

From what you’ve described, it does sound like a bit of a makeshift solution has been left behind where the dishwasher was removed. The gurgling and smell strongly suggest that either waste is being trapped in that section of pipework, or the S bend is not functioning correctly. The S bend is designed to hold water and form a seal that stops sewer gases coming back up through the pipes, so if water is not sitting in it properly, smells will escape even if there is a cap on the pipe.

The fact that food scraps are coming back up through the sink points to a partial blockage or a section of pipe where waste is collecting rather than flowing away cleanly. That trapped organic material will very quickly cause odours, particularly if the pipework layout has been altered or capped off incorrectly.

At this stage it’s difficult to be precise without seeing the pipe arrangement, as the fix will depend heavily on how that capped pipe ties into the rest of the waste line and whether the trap is correctly positioned. If you can upload a few clear photos of the pipework, including how it connects under the sink, that will make it much easier to pinpoint what’s going wrong and suggest the best way to correct it. If you need a hand uploading the images, just let me know and we’ll take it from there.

Please let me know if you have any questions.

Mitchell