We have just completed our corporate building. We are facing bad odour problem in our executive toilet. It is only coming from washbasin (01 no) & urinal (01 no). We have already provided bottle trap in both. It is common line & it goes in to Gully trap. Air vent is also provided. In spite of we are facing problem.
I would like to know whether bottle trap is good enough to prevent bad odour or we have to have provide Nahni trap ( NT )?

It is becoming headache for us.

Requesting to guide in this matter.

With regards.

Pavan Desai - India

The first thing you should do is pull the stopper and shine a light down the drain. You will see a small rod down there. Hair can catch and build up on this rod smell and impede the flow. Take and hook any hair that may be down there. Most bad lavatory smells are caused by rotting hair matted with grease from the soap. Try this. Tonight before you go to bed pour 1/2" gallon of bleach down the drain. Next morning flush the bleach out with, (and this is important) two large pans of boiling water. The bleach will start to dissolve the hair and the boiling water will melt the grease and flush the mess out. Do the same thing with the urinal drain. Drains smell cleaner now? Good luck, Tom