Guests complained about terrible stench during stay

My most recent guests contacted me today to complain there was a terrible stench at 3 am. That smell was so strong and woke them up and the smell lingered for an hour and disappeared. That smell was only in the master bedroom (with ensuite). The rest of thouse didn’t have such smell, and they thought it was from sewer.

I feel quite puzzled about what happened. Because if the smell was from sewer, the other bathroom should have the same smell as both bathrooms share same sewer system.

I have Airbnbed the home for about 16 months, and no one ever mentioned this. I also stay in the house from time to time to do cleaning and maintenance work.

Does anyone have an idea about what could possibly happened? I think if there was a leak of sewer or gas, the smell won’t go away itself. But the guest told me it was so strong to even wake them up and disappeared in one hour. I even called the water company, and they told me there was no maintenance last night and no report by other residents in the area.

If you have a theory, please let me know and thank you in advance!

Also I have actually thought about the guests lying to me because they booked for two nights only and gave me some troubles during booking and check-in. That was quite rare cause 95% of my guests were great. And the rest 5% usually give me trouble during stay and check out.

But I highly doubt people would lie about such thing cause there is no motive behind it. But the whole event does sound very strange.

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No-one here is going to be able to identify a possible cause I’m afraid.

It sounds like you, or whoever you have who manages your property locally will need to go out and check it out.

In the UK gas is odourless, so you wouldn’t be able to smell it.

How did you leave it with the guest?

Best of luck.

Hi Heisi, thank you very much for the reply. The guests didn’t request me to check it because the smell was gone and never come back. They were just letting me know such thing happened.

They are checking out tomorrow so I will definitely check then and I plan to stay there for a night or two to see if there was any smell.

I live in Australia and there is added smell in gas and I don’t think it was gas because people should be able to idetify smell of gas easily. The guests said the smell was very strong, and likely from sewer, but they couldn’t identify the source. If it was gas they would have called me during the middle of the night.

I feel the only way is for me to stay there and check it myself. We have had a pretty busy summer season, there were plenty of guests in the past three months and we had very few gaps. No guests ever complained about such thing. Before the current one checked in, there was a back to back booking, and no problem discovered during that stay. So god knows what happened. I hope I will be able to find out.

Oh dear

This is frustrating. I wonder whether it might be worth getting a handyman or other expert out to double check? This would help if your guests decide to complain.

Also do you have a carbon monoxide tester in the listing, that would help alert you to issues about potential leaks?

Its a good idea about staying to see if you can identify the mysterious smell.

As you had back to back bookings this probably won’t apply.
The waste water trap on some showers these days can be very shallow and only 20mm of water can be stopping the sewer smell from coming in, if the guests haven’t used the shower for a couple of hot days the water evaporates and a nasty pong comes up the trap, it then goes away when someone has a shower and the trap again has water in it.


Dry floor drain - fill it up

Hi Helsi, I do have CO detector but I believe it didn’t ring because guests didn’t mention it. Thanks again for the reply!

@HumptyDumpty, @Debthecat
Thank you both! That could explain smell in some cases but I still think it doesn’t apply in my case. Because I rinsed the shower while cleaning that afternoon. And the smell appeared in the middle of the night, strong enough to wake people up, and disappeared on its own without any work. But I will check tomorrow, live there myself and monitor to see if future guests mention this again.

Hmmm…I can see a discount request coming up ,… :slight_smile: :frowning:


Did you ask them if they had any intestinal troubles or ate a lot of beans for dinner?


Make sure the water trap is correctly assembeled. It happened once to me. Do also make sure it is filled with water.

Likely from their mate! Ha Ha! “No honey, it’s not me! Must be coming from the sewer.”


If they use that as a complaint to AirBnB, I would certainly point out the time, the place, and that it dissipated, and suggest to AirBnB that it was self-produced.

In the meantime, though, you are doing the right thing to look for other reasons that you might be able to address.

A carbon monoxide detector will only detect carbon monoxide which is odorless and is produced in a burning process with oxygen lacking (= heating or warm water system or a fireplace in a badly ventilated room). This usually happens with very old systems that don’t have security built in to prevent the CO production.

CORRECTION: Mr.Google just told me that some ‘smart’ CO detectors that also detect other gases.

@Freya, a few possibilities:

  • If your waste water system is badly designed, the flushing of the toilet could cause the water trap of e.a. the shower to empty itself. But without adding water again, this wouldn’t solve itself within an hour. And this problem should have presented itself before. I would first of all ask the guest, if they did anything like flush the toilet just before they started smelling the sewer. And ask if they did anything just before the smell disappeared again.
  • Or was there a torrential rain that night? If there’s a sudden influx of an unusually large amount of rainwater in the sewage system, strange things can happen too: Apart from the water trap emptying itself, shit could end up on the ceiling.
  • In theory there can also be a buildup of gases in the public sewer. This isn’t common, but if this happens in my home country, the private sewer should be designed to release (a small portion) of these gases through the rain pipes, which should not be smelled inside.
  • Is there any chemical plant, water processing plant, etc. … nearby? I’ve stayed in a hotel in Morocco where each night we would get the horrible smell of the sardine factory. Maybe there was an exceptional event nearby.

I have read that certain kinds of gas leaks can cause hallucinations. I think that includes hallucinations of aromas. This is one theory behind haunted house myths - that the reason people heard, felt, saw, and smelled weird phenomenon is because of a slow leak from old gas systems. I wonder if it is possible that this is the case here?

Any skunks wandering around outside at night?


Well they did not ask for it, and I didn’t provide :slight_smile: . I won’t give discount for some unproven weird thing. Hopefully the review won’t strike me.

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Hi GutHend, thank you so much for giving me such detailed replies.
We never have a history of sudden bad smell inside the house, so the design is probably fine. No rain recently, no chemical plants (or even plants) in my area. And I’m not too sure about gases from public sewer, maybe this could explain this one-time event.

Thank you for the reply! I just checked and stayed in the house for 6 hours and everything seems extremely normal. No smell detected at all, I even disassembled the carbon monoxide detector from the wall and took it around the house but nothing happened. (The CO detector was just updated last year and it was one of the most expensive ones so I assume it works :slight_smile: )

Anyway, slow leak is unlikely in my case, there was no previous sign, and no sign when I checked today.