Unit has 1 bathroom and it smells like sewage

Update: Forgot to post the outcome! It was the flange! Thank the good lord! Lol…thank you everyone!

Question: Maintenance on PTO and I am trying to avoid a plumber if possible. This unit has 1 bathroom and it smells like sewage. I have checked the drains and they are clear, the p-traps are not dry because there are 3 occupants using 1 bathroom and I checked the clean out just in case. What could be causing this?

Check floor drains in utility closet and by washer and dryer

Heavy use for the toilet could be wearing away at the flange, if it's not sitting correctly and holding the water, the sewage smell could be seeping out from the wax ring area or if bowl isn't holding enough water it could be coming back up through bowl

Wax ring on toilet?

Run a small plastic drain cleaner through the sink and then run hot water for 10mins

Could be caused by several issues. Vent stack could be cracked/damaged allowing sewer gas in. Could be an issue in another unit connected to this unit and this is where the smell is coming to. Could me a city main line issue (though more units would probably have a problem if it was)

Or could be the line is clogged and needs to be snaked

Thanks so much everyone! I actually thought about the flange and then dismissed it. I will pull the toilet and replace flange. Fingers crossed!!!

Just had this happen to a toilet. The flange was installed at a tilt so it wore out faster smell was very light until the toilet was pulled then it was much stronger

Do you have plank in your bathroom? If not sealed right water can get underneath and smell horrible!!!

Molding hair in the sink drain

Have had this problem in my house for 3 years!!! Wits end. Pretty sure it’s a busted pipe under the concrete subfloor. Super frustrating.

Get a new synthetic wax ring. Easy to replace with 2nd set of hands.

RESPECT to you doing everything you can before thinking of calling out a contractor.... so many would say not my job in today's world. This is my I love PROPERTY MANAGEMENT it's where all the die hard good workers end up such great support surrounding us all.

Had this problem in townhouse style property- cracked sewer pipe under the unit in crawl space.

Not in the bathroom but your condensate drain/stand pipe could be dry allowing smells to come up from the main.

Sounds like a cracked pipe somewhere

First, I would clean the sink P-trap you cannot believe what I have pulled out of there and it was stinky.  If that's not it and the unit is on the bottom floor, you could have a cracked or broken sewage pipe in the crawl space, I have that happen a few months ago.  

Good luck.