Sink drain is slow and flowing into other sink. (No garbage disposal). I Noticed water was spilling over from under sink vent
I had the same issue from hair, toothpaste, soap scum. No need to remove the trap or use harsh chemicals. Try buying one of these sink plungers. Fill the sink with hot water, then open the drain and after a second or two start plunging. I've done this several times and now I do it as soon as it starts to drain even a little slow.
It's possible the sink vent (air gap) is clogged with debri. You would need to remove it and check/clean out any debri. Replace the vent and see if the sinks drains and no water is coming out of the vent. If there is you may have a clog further down the line and/or may need to replace the vent.
Vinegar,baking soda and plunger works for me
I have a handy man who told me not to use harsh chemicals. He told me to pour a cup or two of blue dawn dish soap in the drain and, without using the drain, in a half hour or so pour in boiling water and run hot water to get everything to move. I've used that method on my kitchen sink and bathtub more than once. worked well and was so much better for the environment. I was amazed!
I had some very old GoJoe which had melted out in the shed heat, probably about 1/2 cup. I poured it down my slow running drain and walked away, leaving it for several hours. Then I turned on the hot water and flushed it really well. That drain has never run that well since I moved in 5 years ago. YAY! I plan to buy some more GoJo...just in case. (I guess you buy it in the auto parts stores.)
just had this happen to my sink, the old cast iron original pipe that was under the sink cabinet cracked open and was leaking. Quite disgusting, he replace pipe, now the sink drains. I use vinegar and baking soda monthly on all my drains
If you've never cleaned the drain prior, let's start at the beginning. Get a needle nosed pliers and paper towels. Remove the plunger from the drain (or whatever it's called that plogs the sink with water in it). Reach in with the needle nose pliers and pull up whatever you snag. If this is a bathroom sink, you'll likely get a bunch of hair, soap scum and other yucky stuff. Wipe on paper towels and repeat until you can't get anything else out. Also wipe out around the overflow drain (if you have one) on the side of the sink and as far down as you can reach.
You can get any one of those new disposable long plastic hook thingies but I actually get more gunk with the needle nose.
Next, pour a good 1/2 cup or so of baking soda down the drain and follow with white vinegar. You will hear hissing and see foaming but don't be concerned. It's just the chemical reaction of an acid (vinegar) with a base (soda) and is good at dissolving biologic scum like soap. Add more vinegar as needed until the hissing stops. Follow with running hot water for about 5 minutes.
Finally, pour about 1/2 cup original blue Dawn dish soap down the drain and allow to sit an hour or more. Again, run hot water for at least 5 minutes.