I have just moved into a new house and have no idea how the plumbing under the sink works but whenever water goes down the sink at a certain rate it, some of it comes out of a small pipe underneath sticking slightly upwards out of the main pipe before the trap. The pipe has an adaptor on it which looks like a hose connector. Is this an overflow pipe of some sort which is missing somewhere to overflow to? Or should it have a stopper on it? Anyone have any ideas? Thanks

Is this what you have ?

Yeah, very similar...

Do you have a dishwasher or garbage disposal?


That connection is typically used to attach a dishwasher drain line. If no dishwasher or dishwasher attached to disposal then you need a straight tail piece similar to this. They are sold in home centers and aren't to hard to replace I'm not sure exactly what your configuration is under the sink but it shouldn't be too difficult. Post back if I missed anything. GOOD LUCK, AC

I don't have a dishwasher or disposal but there is a supposed to be a washing machine next to the sink, which I haven't filled yet as the old owner took it with her. Would that be the same idea? So as soon as I get a new one installed the problem will be stopped?

I don't have a dishwasher or disposal but there is a supposed to be a washing machine next to the sink, which I haven't filled yet as the old owner took it with her. Would that be the same idea? So as soon as I get a new one installed the problem will be stopped?

AC101 did a excellent job of describing your situation. This is indeed a branch tailpiece the original owner left open when she took her dishwasher with her. Your open cabinet space is for a dishwasher , not a washer.
Slip a baggie over the open branch and secure it with a rubber band until you can install another dishwasher. Don't forget to run a high loop, (see image) on the discharge hose when installing the DW. To answer your question

So as soon as I get a new one installed the problem will be stopped? It sure will! Good luck, Tom

Brilliant, thanks for all the advice. Still a little concerned about the dishwasher point though because the appliance in the space was definitely a Washer Dryer for clothes and not a dishwasher. Could I still connect in the same way?

The set up was originally for a dishwasher. A washer would have to have a high loop instaloled for a air gap the same as a DW. I can see drainage problems in the future discharging a washer into the sinks lateral drain line in the wall. It's bad enough with the garbage that you're sending down the line. Adding lint and fiber to the mix only ups your chances for a clog.
Good luck, tom

Many thanks, will keep it all in mind!