I Just purchased a 55 year old house. The upstairs toilet bowl was empty for some reason but the tank was full. This toilet was disgusting so I replaced it. I have noticed that when I flush this new toilet on the upper floor a large air bubble comes out of the toilet bowl in the toilet in the bathroom right below that one. I'm thinking blocked vent line. What do you think?

Thank you in advance,
Todd

Hi Todd,

I'm thinking you're right. What's happening is then you discharge the upstairs toilet it pushed a bubble if gas down the stack and it came up in the downstairs toilet. This would not be happening if the upstairs toilet was allowed to vent itself. Your vent's indeed blocked. A little more information. Flushing the downstairs toilet will produces a vacuum since theonly air it can pull is trapped in the vent because it's blocked. The vacuum will seek to vent through the upstairs traps and toilet bowl and pull water (the trap seals) out. Clear the vent and you'll be OK Regards, Tom.