Why does flushing one toilet pull water out of another?

“Bought a house 3 months ago, the bathroom sink was a little stinky. Tried some hot water and dishwashing liquid which helped a bit but only temporarily.”source ↗

“My bathroom sink is smelly!!! 😳 but thank you for the info, I dread the idea very very much. 😁”source ↗

“Every year when it starts warming up this floor drain smells disgusting. Not like sewage but like still nasty moldy water.”source ↗

“When I run water it slightly clears up and smell goes away for 12 hours but the smell is back after that.”source ↗

“The drain currently does have water in it and has never been dry anytime I took the cover off. The water that’s sitting in there is black and disgusting.”source ↗

“However, lately there has been a foul odor from the kitchen, but we can't pinpoint where it's coming from.”source ↗

“So my question is, was I lied to by the installer?”source ↗

“We bought this place about 6 months ago. It's on a septic system and we have noticed a septic smell under the kitchen sink every so often, and it comes out of our bathroom REALLY bad whenever the barometric pressure drops during a sudden storm. But here lately I've been smelling it almost all of the time coming from our bathroom.”source ↗

“I'd love to just pay someone to come figure it out and fix it, but I just don't have the funds right now.”source ↗

“I’ve been dealing with a persistent sewer/drain smell coming from the cabinet under my kitchen sink and I can’t figure out where it’s coming from.”source ↗

“A plumber has already been here and cleaned the trap/siphon and the accessible drain parts, but the smell is still there.”source ↗

“We get a horrible smell coming from the shower drain on-and-off that makes me gag, and me are having issues with drain flies.”source ↗

“Smells like sewer gas in the bathroom since.”source ↗

“My wife and I have been smelling sewer gas in this bathroom since the day we moved in, and I’ve been trying to track down the source.”source ↗

“Whenever we flush the toilet in Bathroom B, the water in Toilet A gets heavily disturbed and pulled down.”source ↗

“I’m completely lost at this point. Why didn't the open air intake (open vanity) relieve the suction on that trap?”source ↗

“That trap is most likely dry letting sewer gases in.”source ↗

“Made it a P trap. Still stank.”source ↗

“Added an AAV. Results pending.”source ↗

“I had some plumbers install a new vanity, and I noticed after installation that, after I run the tap, a sewer gas odor seems to emanate for some time.”source ↗

“I noticed the smell coming from the bathroom (we have a septic) I think it’s the sink here because we had to put a reverse P-trap”source ↗

“Sewer smell coming from this bathroom sink area (though I have not definitively confirmed it is the source).”source ↗

“For the last 5 months or so, my dad’s house where I currently live has had a sewer gas smell come and go.”source ↗

“But the smell seems to keep coming back every week to every 2 weeks now even with using all the drains in the house.”source ↗

“Backwards p-trap on new construction is hysterical. How inexperienced do you have to be to screw up a vanity stub out.”source ↗

“When we first moved in, there were a lot of drain/sewage flies, along with significant humidity and a musty smell in the basement.”source ↗

“I brought up the open sump pit with our property management company, but their director told me the gap needs to remain for airflow.”source ↗

“When I bought my house recently I began noticing a rotten egg smell coming from my laundry room in the basement when the detergent pump went off.”source ↗

“It could go weeks without smelling it but every now and then it stinks up the basement.”source ↗

“I also noticed I don’t have a p trap under my sink I’m not sure if that’s necessary or not.”source ↗

“Bad odor coming from this area.”source ↗

“if the floor drain is your smell issue, you can get a one way trap device that lets water in but not smells out.”source ↗

“The issue we've noticed is sometimes we smell a sewer type smell coming from under the sink.”source ↗

“yesterday we noticed the sewer like smell - and I'm wondering if it is coming from that open drain line.”source ↗

“for the last couple weeks I’ve noticed a strong sewage smell when my dishwasher starts.”source ↗

“Help!! -a poor homeowner 😭”source ↗

“My house has a sink that emits a sewer smell.”source ↗

“Is this something that is fixable without cutting a hole in the bottom of the cabinet or cutting into the wall?”source ↗

“Hello, put this trap in my shower pan. Smells like sewer gas in the bathroom since. Please help?!”source ↗

“I wanted to clean the p trap because the bathroom has a strange odor”source ↗

“I lifted it up and didn't notice any immediate flooding, but there is a sewer smell / a lot of dust / bugs.”source ↗

“Is this a makeshift fix for a dried-out P-trap, or is there a structural/plumbing reason someone would leave a bucket like this?”source ↗

“yeah that's straight up missing a p-trap, i can see the disposal and the pipes but there's nothing creating a water seal to block the sewer gas coming back up”source ↗

“When I take a shower in the morning there always a really strong eggy/sewer smell.”source ↗

“I’ve tried using drain unblocker and nothing has changed”source ↗

“I’m having an issue with sewer gas smell in my bathroom.”source ↗

“After reinstalling the toilet I thought the smell was gone, but it came back the next day.”source ↗

“Put a brand new wax seal in (again) and reinstalled the toilet. Still, the smell persists.”source ↗

“was doing everything in my power to stay away from PVC and then had to convert, prime, and cement because of the AAV 😞”source ↗

“We're going to have a plumber come down next week and snake our main line/pipe/whatever as we had a bit of an incident today (waste appearing in the shower, toilet's been clogged for a week”source ↗

“I'm just wondering how do plumbers deal with the smell and is there any etiquette I should take to make the process easier?”source ↗

“This bathroom often smells pretty bad.”source ↗

“I have a sensitive sense of my smell and my partner has the opposite: almost no sense of smell at all. He doesn’t smell it but I smell it almost every day.”source ↗

“I believe that it is most likely coming from the shower drain but I wouldn’t rule out the toilet. I smell it the most when I sit on the toilet to go the bathroom but at times it greets me as I walk through the bathroom door”source ↗

“the smell has been present for idk? Maybe close to a year on and off? Some days are better than others.”source ↗

“Any suggestions you have for eliminating the smell would be appreciated.”source ↗

“My wife and I have been smelling sewer gas in this bathroom since the day we moved in, and I’ve been trying to track down the source.”source ↗

“Whenever we flush the toilet in Bathroom B, the water in Toilet A gets heavily disturbed and pulled down.”source ↗

“I’m completely lost at this point. Why didn't the open air intake (open vanity) relieve the suction on that trap?”source ↗

“There is a drain pipe located behind the dryer and washing machine, and it is emitting a foul odor resembling sewage. What kind of pipe is this, and how can I deal with the smell coming from it?”source ↗

“We bought an old house in Quebec (built around 1890) a few months ago, and we’ve been dealing with persistent sewer smells. At this point, the smell has become extremely strong and is starting to permeate the house/clothing, and we’re really at a loss.”source ↗

“However, the sewer smell has continued and has now become much stronger, despite the leak being repaired.”source ↗

“What would you investigate next if this were your house? Any advice on what specific tests we should ask a plumber to perform would be greatly appreciated.”source ↗

“Previous homeowners left this old pipe uncapped. Our basement intermittemtly reeks of ammonia, and on cool nights, the smell rises into the house.”source ↗

“When we turn on our whole house fan, we get a sewage smell in the house upstairs.”source ↗

“The smell is not particularly strong around either of the two toilets that were installed. But it’s very strong in other areas upstairs.”source ↗

“the house has an unbearable smell in it. It’s coming from the laundry room but filling the house.”source ↗

“How do I get this smell out of the house?”source ↗

“I ran the water in the laundry room and bathroom (next to laundry room) last night already”source ↗

“I did that last night. Just keep doing it? No windows on the main floor that open, just a slider door. The rest are huge windows but they don’t open!”source ↗

“every time my AC is on my unit smells like rotten food.”source ↗

“Does my AC smell because of the sewer plant or it might be something internal?”source ↗

“But now there is a foul smell in this utility closet.”source ↗

“Im guessing the plumber removed a trap some where down the line.”source ↗