[alexander]

Thanks to those who have provided previous info. Here is more detail' single story house on a slab. three toilets running from back to front of house. the smell is in the front room which has an adjourning toilet. not often used. the smell happens only occasionally and usually clears after about two hours. no sign of line breakage . the only thought I have is traps drying out or perhaps vent pipe clogged up. anyone out there have any suggestions? Thanks, Mike