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Dishwasher not draining, kitchen sink and bathtub draining slowly? Answered

Recently everything seems to be draining slowly. I snaked the bathtub and removed a chunk of hair but it's still draining slow. My dishwasher isn't draining properly and the sinks partially fill up when dishwasher is running. Also the kitchen sink drains slowly. Could this be an air vent block? Last winter we  had a similar issue with our kitchen sink, after snaking, baking soda and vinegar etc it still would not drain well. We thought it might be ice buildup in the pipes? If it is an air vent block how would one go about unclogging? Also is there any chance the air vent would come out of the side of the house and not the top?


Water will drain whether or not the vent line works. If it does, the flow will be smooth and rapid, if not, You will likely hear a gurgling from somewhere (a nearby drain connected to the same vent, or the sink itself, when water is draining.

My suspicions, based on themany different drains that aren't working is that your mian drain is partially plugged, and at a guess, unless you've stuffed everything down the drain and plugged it with food or sundray paper, you have roots developing in your sewage line.

I live in a ~120 year old home, and the main sewer line is afaik original. I have to use root killer periodically, as do many with older homes. Eventually, if you don't, the roots will grow beyond a mere nuisance into a serious problem.Hair fine feeder roots have an easy time finding any (and all) gaps in the drain through which they can access that water flow. Once there, they will grow fatter and fatter as they develop secondaries. once they reach a certain point, they'll crack you drain pipe and the only solution will be a very expensive sewer line job. Maintenance pays.

Once they've found your "free water supply", they will never forget and will come to rely on your water outflow especially in times of drought. Be vigilant.

good luck!

BTW< since it's draining so slowly, my guess is that you'll need at least one thorough sewer line snaking before maintenance is useful.


3 years ago

An interesting thing with the plumbing air vents. The are more for letting air in than out. In order for the water to run down the drain pipes, a process that is gravity fed, you need to allow air to enter above the line. Otherwise the water going down the pipe would create a vacuum and would slow down the flow of water. Air would have to bubble up from below to break the vacuum or get sucked in from the house drains. Since that would pull all the water out of the traps a vent pipe is needed to allow air in to break the vacuum and let everything drain.

Some sewer gas does come up and escape from the vent but that is not the main purpose of its design.

It appears that you have a partial blockage somewhere in the drain system. If all the drains are running slow then its in the main drain and could be something like tree roots. If you have one drain that is working normally then the blockage is between it and the rest of the drains.

My son had a squirrel climb into the drain vent on the roof and then got stuck and died in the line between the kitchen and the bathroom. He had to rent a long clean out snake and push the dead squirrel all the way down the line until it finally reached the larger pipes and went the rest of the way on its own.

And another thought. If one of the air vents was blocked you would be able to verify that by disconnecting a sink trap and then flushing a toilet. The water going down the drain would draw a lot of air into the pipe from the sink. Drawing in some air would be normal but if you were to place your hand over the pipe and it created a strong vacuum then it would indicate a blockage in the vent somewhere.

It sounds like a block in the vent. No the vent comes out of the roof top. You don't want it coming out the side of the house cause then you would have sewer gases leaking into the house.

To fix it you'll want to call a professional unless your comfortable climbing to the roof to snake it yourself. Asumming you have a snake handy that can reach far enough down to clear it. I would just call a plumber. They'll be able to scope the pipes with a camera and find the problem.

Blocked drains. To determine where the blockage is will require opening the inspection points outside. If those are empty then the blockage is between there and back to the sink/bath junction, if its full and water gushes out, then the blockage is further on towards the mains.