If you can find it get some drain open crystals. Hard to find because of meth heads . But best way run sink snake down it . Unless you got a nest in the vent that’s not the vent

Yes, I took the trap apart and checked it, it was clean. The first time I took it apart some time ago it was messy, I cleaned it and it has remained cleaned since then. I am 77 years old and I don't climb up on roofs nowadays, lol. Since this problem seems to correct itself after a day or two of slow drainage I guess I can live with it. I was just curious as to what could cause this problem. Not sure how the venting works. Would it be possible if we had enough rain the vent could get flooded a bit if there was something clogging it a little and then after a period of no rain the water would drain from the vent and then the drain would work again?

I hear ya on the roof climbing.

A lot of odd things are possible especially since we can't see exactly how that vent line is situated in the wall .

I am going to assume that the sink drain tees into the toilet drain and that both are on the same vent....Shower/bath also . If that assumption is correct, and if the toilet and tub drain normally, I would say there is some clog below the sink trap but ahead of the toilet main line,

Can you see the vent or vents on the roof ? If so, can you judge the diameter of the pipe ?

Plumbing work is sometimes a crappy deal .That being said I would pull the trap off and run a snake( metal one preferred-no rattlers) from the end of the pipe where you disconnect the trap. I think you have a blockage. The bill is in the mail. I do not except government payments.

Get you some orange degreaser and pour in it at night let it stand. It will break do the sludge . Then get you a big pot of water and bring it to a boil on the stove . Dump it down the next day . Good luck

If it is a frozen over vent, buy or make a sewer vent defroster. Google it. I made one and if it works in far northern WI it will work where you are at.

Here's a thought. Take that trap out of the line and just pour clean water down the pipe. You should be able to tell by listening if it is filling the pipe or going down the drain. If it fills up put some Draino down there with it and let it sit

I have opened up drains on sinks and smaller gray water drains with a shop vac before. Set it up for wet pickup, you can switch hose from vaccum to blow. Suprised how years of small debris builds up to slow a drain.

this would be my choice too.my parents drains were backing up in the kitchen and bathroom. I thought slim chance both traps would be plugged. they weren't went to the basement and took the cap off of the cleanout and run the sewer tape thru it and got it unclogged.

i'd try this. that draino stuff is a waste of money. a small snake if it don't work.a $100 dollar snake at harbor freight will work if you want to do it yourself.

Here's a old plumbers trick...Sprinkle 1/2 cup baking soda in the drain hole, then pour a cup of white vinegar in with it, and listen to it fizzle as they react.

When the reaction slows down or stops, wash it down with hot water heated in a coffee pot...Might have to do it a couple times to eat away the scum, hair, etc.

Better than draino, and other similar products.

I just used one of these kits and an electric pressure washer to fix the slow drains at my house.. the kit provides everything you need to Jet a drain line..Will work with either electric or gas pressure washer.

and I have the tool for future events or preventive maintenance.


from amazon.

https://www.google.com/search?client=firefox-b-1-d&q=POHIR+Sewer+Jetter+Kit+for+Pressure+Washer

Also works for your downspouts and other drains

hot water! thats what I try second after checking the popup

At the present time the drain is open, in fact, I can turn both hot and cold full blast and the drain doesn't back up. It just seems strange to me that once in a while it will back up and then a day later it is open without me doing anything. The backup does not occur very often.

Is it close to your tank ? You might be on the verge of big problems. Are you washing clothes when it happens? Good test is next time it happens flush the toilet see if it goes down normal or slow. Things like this are process of elimination

Do you have a septic tank? Does it need emptied? It would seem that you would have issues with other sinks/tubs/toilets if that was the issue……..

I had the same issue this nov. Actually it has been getting worse the last couple years. My main sewer line was full of roots. Had to replace 30 feet during trapping season.
Sure won't hurt to flush a cup of copper sulfate. I know I will.

if your on a septic system it could just be the ground water coming up to meet your tank not letting it drian !

What is your weather right now ?

Pressure related ?