Under sink plumbing - what's wrong?

WLSM

Hi,
Fitted a new sink and new under sink pipes - only old pipe is the vertical pipe going into the ground, which once under the floor travels about 4ft and drops into the outside drain, seems to flow alright outside.

The water is not draining as it should, air seems to be getting trapped in the P-trap and gurgling back for about a min after as the water returns to the right level in it.

Should I have used a U-trap, should I put a vented pipe/valve in on the horizontal?

Any advice is much appreciated.

Photo of piping is below:

Billy Bunting

Only issue i would have is your waste from your washing machine, you should raise the gray pipe to prevent waste water from the sink entering, the rest looks fine.

freddyuk

You could fit Hepvo traps
http://www.hepvo.com

No water to cause an issue then. They can go vertical or horizontal. Come with adjustable elbow fittings and easy to install with compression fitting.
I have one in my bathroom and no issues. (I didn't want to see a big trap under the sink).
You may be able to just install one horizontal in your twin bowl set up providing it complies with local regs. Or better still in the vertical downpipe?

WLSM

Thanks guys