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Friday, October 09, 2015


There has been a strong sewage odor in the public restrooms of the building that we can't seem to get rid of. This is a retail facility and the strong, unpleasant sewer odor obviously decreases sales. There are sealed toilets, extended vent stacks, working p-traps, no real noticeable causes. What might be the source of this? How can we get resolution to this problem?


There is only one source of sewer gas and that is the sewer. You have checked the obvious. The toilets and urinals are self-trapping and as long as water is visible, the trap is in place. The traps under the lavatories and p-trapped urinals are easily checked and there is no problem there. So what is left?
If there are floor drains in the rest rooms or elsewhere in the building (furnace room?), the traps down there may have dried out allowing gas to escape. Simply pour some mopping or disinfectant solution down each drain to refill the trap.
The vent stacks are easily seen above the roof and they may be extended, but is there any possibility that a vent is located near a fresh air intake for the forced air heating system?
Someone needs to check also above the ceiling to see if any vent lines are disconnected from the main stack. Any breaks or openings in the venting system in the attic or above a suspended ceiling could allow the heating system to draw fumes into the cold air returns and disperse them throughout the building. In fact, some heating systems use the entire area above the suspended ceiling as a plenum for cold air return to the furnace. Even if you have another type of heating system, an open or disconnected vent pipe is still a good possibility as an odor source.
In short, there is an opening in the sanitary sewer venting within the building. Start looking where the odor seems strongest. Keep searching until you find the problem and can end this most unpleasant air pollution.
Lynn E. Krafft, ICAN/ATEX Associate Editor