Sewer smell strong in trailer when dumping??

[ivbinconned]

When he dumps and the hose all sealed from trailer to ground they get a strong brief smell in the trailer. Windows and doors all shut.
What’s going on here?

[Lwiddis]

He is a great Chinese name but I don’t encounter it much in the states.

[Lwiddis]

He should check the roof vents.

[Dick_B]

Any chance the bathroom exhaust fan is on while dumping?

[redhooker]

If equipped with washer hookups check that the drain is either capped or has water in the trap.

[schlep1967]

Air admittance valve under one of the sinks is probably bad. You can get them for a few dollars at the big box stores. Google it to see what they look like.

[ScottG]

Maybe it's the grey you smell. If the roof vents are installed wrong or blocked for any reason, dumping will pull water out of the traps and it can smell.
Grey can smell worse than black.