I've checked the toilet and it flushs quickly. I checked the drain in the sink and it works well. When I flush the toilet I can hear it working at the floor drain located 7 feet from the toilet. It is NOT backing up? The store sells cosmetics so the sink is used to wash cosmetics off brushes? Could they be building up in the drain? We've had 60 days of extreme cold weather below freezing. Could the stack vent be frozen over be the cause?

The floor drain is the problem. It appears it has no trap ( or broken trap ). Trap prevents sewer gases from entering room. Trap also mutes sound of rushing water after toilet is flushed.

You have two choices how to deal with it:

1. Remove the drain cover, insert plug into the drain, and put cover back. This way you won't have smell in the room but the drain will not be functional. This is a quick and inexpensive way of dealing with this problem.
2. Cut open the floor, install trap. This approach will require a professional to do the work. Depending on what type of floor you have, it can take all day to do and may cost you few hundreds of dollars.

But in any case, you should deal with it as soon as possible as sewer gas is a health hazard. You certainly don't wanna work in a room with sewer gas present.

Hope that helps

Milo

Hi milo
Your answer assumes a broken trap in the floor? How can you be so sure when nothing is visible? This large Mall / store has been here for many year( (40 years)and what your concluding is a major collapse? The smell JUST started in late January. Could it be that the "Ice Over" has "reveleed" a flaw in the original plumbing design? - don't want to jump to conclusions and tearup the floor only to find -m wrong? Ouch!

Do you own this building? Are you responsible for repairs?

NORAM: You did not mention in your original question that the smell became obvious this last January. This is a new info into our discussion...

If the smell just started recently than:

Every commercial trap should have a Primer installed and that Primer has to be activated. Locate the Primer valve and make sure nobody turned it off. I turned off, water inside the trap will dry out and trap will prevent sewer gases to pass through the trap and into living spaces. Trap primers have to run 24/7.

To assure the trap in question is holding water, take a flashlight and look through the cover inside the drain. There should be standing water. Investigate and let me know what you have found out.

Back to you

Milo

Do you own this building? Are you responsible for repairs?

No we work for the FM companies and their clients. This is a massive Shopping Mall with 000's of stores. Its roof is 7- 10 stories high

NORAM: You did not mention in your original question that the smell became obvious this last January. This is a new info into our discussion...

If the smell just started recently than:

Every commercial trap should have a Primer installed and that Primer has to be activated. Locate the Primer valve and make sure nobody turned it off. I turned off, water inside the trap will dry out and trap will prevent sewer gases to pass through the trap and into living spaces. Trap primers have to run 24/7.

To assure the trap in question is holding water, take a flashlight and look through the cover inside the drain. There should be standing water. Investigate and let me know what you have found out.

Back to you

Milo

Hi Milo
Yes there is standing water in the drain. That is the problemand why I posed the question? There are NO anomalies anywhere except for the extremely cold weather and the smell. It's a strange problem. The store uses cosmetics that they wash into the sink. I'm thinkoig
That the cosmetics congealed in the cold sewer water and could somehow be contributing to this issue. I'm going to snake the lines to 125 feet and see what happens. Were finally above freezing tomorrow after 2 very cold months. The coldest February ever recorded.

A trap primer is a nice thing, but it is not always found at all floor drains. Either way, pouring water into the trap would stop the odor issue if prime/water loss at the trap was the issue.

If weather has been below freezing for a long time now (as it has been in my area), then I suspect a frozen vent and an unvented floor drain. Here, if a vent froze for any particular drain associated with the floor drain and the floor drain was unvented the fixture affected by the frozen vent could vent itself through the floor drain... effectively burping sewer gasses back into the space.

You can check this by having someone use all the nearby fixtures (and fixtures on floor above) and watching the water in the floor drain... if she burps, you found the problem. Fixing it could be a little harder, but since you guys are thawing out, I'm figuring you'll figure this out quickly!

Otherwise, snaking the drain and bleaching the drain line with a 20%bleach solution can't hurt anything!

Mark