I recently purchased a house (35 yr old) in which the kitchen sink vent was removed (it was completely clogged). The plummer installed a mechanical vent for the sink drain. That works fine for the kitchen, however when a toilet is flushed, water actually backflows into the kitchen sink. I am guessing the vent servicing the bathroom is also clogged. If this vent is unsnakeable, what are my options?

Thanks!

A clogged vent wouldn't cause your sink to back up. You have a partial blockage down stream from the kitchen sink, To unclog this you're going to have to remove the AAV and snake from the kitchen vent. You didn't say but I'll bet this is a second floor toilet that's making your sink back up.
Good luck, tom

The toilet is on the first floor. The drain line from the kitchen (the line starts at the kitchen, goes approx 20 feet, and there the line from the bathroom connects) looks to be relatively new 4" PCV. It seems weird that flushing a toilet (downstream from the beginning) would cause water to appear in the kitchen sink, particularly if the line from kitchen to where it intersects with the line from the bath is partially clogged. How does that happen (excuse my ignorance)?

Thanks!

Quote:

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Originally Posted by jztpoolinu

The toliet is on the first floor. The drain line from the kitchen (the line starts at the kitchen, goes approx 20 feet, and there the line from the bathroom connects) looks to be relatively new 4" PCV. It seems weird that flushing a toliet (downstream from the beginning) would cause water to appear in the kitchen sink, particularily if the line from kitchen to where it intersects with the line from the bath is partially clogged. How does that happen (excuse my ignorance)?

Thanks!

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The toilet's downstream from the sink with a tub or shower it could back uo into? Instead it defies the law of physics and backs up a over good two feet of elevation and comes out in the kitchen sink.
Some where I'm missing something because unless the laws of nature have been repealed water will still seek its own level. What am I missing? Tom

When the bathroom toilet is flushed, a gurgle and small amount of water will come from the kitchen sink (p trap perhaps). The kitchen sink has a new under the counter mechanical vent. I suspect the vent pipe for the bathroom (one that goes through the roof) is completely clogged. If that should be the cause, is there an alternate way to vent the bathroom (without removing the 35 year old cast iron vent pipe).

Thanks & Have a Good Weekend!