Basement utility tub drain and odors

[SMcLaughlin]

Every now and then my utility tub drain, which is located next to the main sewer clean out, will give off some offensive odors if the the upstairs toilet or shower is being used. There does not seem to be any "P" trap in the drain as it dumps directly into the main 6" line located not more than 12" away. Is there anyway to stop the odors? I have to cover the utility drain every time I entertain guests in the basement. :mask:

[majakdragon]

Having a trap in the line is the only way to prevent sewer gases from entering your basement. Traps form a water seal that keeps the gases in the drain line.

[Stevetra]

You should place a "P" trap on that utility drain.
The trap will hold water and block the sewer gasses from escaping.

[michiganguy]

Sometimes the reason people ''forget'' to install traps here is a trap can cause

enough back pressure in the line to make the pipe overflow. The drain pipe

may need to extend as far as possible above the trap and the drain pipe

diameter should be adequate to handle the flow without backing up.