We have a foul odour in our master bathroom. I suspect its from sewer so we had a plumber come in and he snaked the vents and put a very expensive drain cleaner into the drains but the odour is still there - its quite strong at times.

In order to troubleshoot, I closed off the drains - sink, bathtub and shower by closing them and putting stagnant water in the tub and sink (duct taped the overflow) and duct taped the shower drain. The odour did not go away. The toilet has recently been replaced and a new wax seal was used. The toilet also has silicone sealant around the base.

We've endured this smell now for several months - sometimes its really bad and other times a bit milder but always there.

So, having closed all the drains and since the toilet is sealed at the base, how the heck is the smell getting into the bathroom? We have an adjoining bathroom (other side of the wall) and it doesn't have the odour. The only other opening is the bathroom vent and we tried sealing that off but it had no effect on the smell.

The plumber from Roto Rooter suggested he come back and put a camera down the vent and perhaps snake it again with a smaller diameter snake. Charge for that would be about $700 - $1,000 and no guarantee of success. I'm reluctant to hire a plumber and spend really big bucks with no guarantee of successfully getting rid of the odour.

Before I call another plumber any suggestions what I might try?

Billdon

The plumber from Roto Rooter suggested he come back and put a camera down the vent and perhaps snake it again with a smaller diameter snake. Charge for that would be about $700 - $1,000 and no guarantee of success. I'm reluctant to hire a plumber and spend really big bucks with no guarantee of successfully getting rid of the odour.
$700 to $1000 is a lot of money to lay out on a "maybe".

we had a plumber come in and he snaked the vents and put a very expensive drain cleaner into the drains but the odour is still there
I am no fan of putting harsh chemicals into your drainage system. Sounds like a rip-off to me. We snake lines out so we don't have to use Draino or Whatever, and his statement that if the large snake didn't clear the vent he would come back with a smaller snake and a camera, along with a service charge that would pay for his Aruba vacation, is downright laughable. Where do you find plumbers like that. Did you ask if this clown was licensed?
You sound more knowledgeable to me then the "plumber" you hired to do the work. Was this plumber from Rotor-Rooter or someone from a real plumbing company?

So, having closed all the drains and since the toilet is sealed at the base, how the heck is the smell getting into the bathroom?
That's what you and I are going to find out. The odor just has to be stronger at one spot rather then another. How about inside the wall between the two bathrooms. Could a pipe have opened up inside the wall? Has any one even bothered to poke their head up in the attic to see if the source is there? Was the vent snaked from the roof? You have, in my book, done a far better job of tracking down the smell then the people you hired. You're well on your way to locating the source of the odor. You have elimated the most likely spots. Now it's time to think outside the box. Sadly, some plumbers think that means coming back with a higher charge. Do some more sniffing around and get back to me. Is there a closet or some spot that you could open a small hole in the wall between the two baths?
You're there, I'm not! You're going to hafta be my eyes and hands. Work with me and we'll track "ole stinky" back to his source. Cheers, Tom

Tom,

The bathroom has a sink, toilet, shower and tub. There is also a bathroom vent. When the plumber snaked the vents from the roof (flat roof - no attic) he indicated that the one going to the bathrooms were difficult to snake through and complained that he nearly broke his snake which was why he suggested a smaller one be brought back. He also said there was a white substance on the end of the snake. I thought maybe the vent was plugged up and so to test that theory I closed off all the openings to the bathroom but the smell was still there.

Will try to determine if the smell is stronger in a particular area although so far it just seems strong in the whole bathroom. My wife did say that the odor became stronger after the shower in the other bath was used.

If there is a pipe break between the two bathrooms wouldn't the other bathroom also have a smell? The sink has a vanity/cupboard below it where the plumbing is located (shutoffs, trap etc.). The wall that is against the other bathroom is fully mirrored and there is a low shelf with cupboards below that is beneath the mirror. The only way to potentially cut a hole between would be from the other bathroom just above the toilet.

Is the purpose of the small hole to try to detect odor from in between the walls?

Be happy to send photos by email.