A vacuum is being created at some point after the two drainage pipes meet. This forces air back up the other pipe and through the "U"-bend underneath the sink, causing the water to gush upwards and drain again, making the gurgling sound.
Since both the bathroom and kitchen gray water supplies contain no sewage, this not harmful.
There is a blockage in your main sewerline.
Odds are you have a problem wth either your vent pipe being to small or not located in the proper position to vent the waste line. What I would suggest is installing a vent pipe on the sink if there is not one already. Another option is to buy one of those pop-vents that actually goes under the sink or install a vent at the toilet.
When you get that gurgling sound it is because the Drain pipe is not pulling in air. It is creating a vacuum an the vacuum pulls on the line and the toilet will gurgle and let in enough air to compensate.
Bath sink is not vented properly so it is using the kitchen sink as the vent.
Bathroom or kitchen should be square and level. The plumbing drain lines need slope to drain properly.
By properly sizing the vent by fixture units and developed lengh and pitching it up from the fixture it serves
In a conventional household, water from a kitchen or bathroom sink flows down a drain. This drain leads to a storage compartment that is periodically emptied.
Yes, if you do not use them often and have poured sugary substances down the drain.
the plumbing drain vent is not installed or poorly installed.
What makes a bathroom drain smell, soap makes a bathroom drain smell
Because the washing machine drains down the same main drain and it's suction as it goes by is trying to suck the water out of the under sink U trap.
You have a blockage in your main sewerline. You have a problem with your venting system. This is why some codes now require a vent within 6" of the toilet. If you will add a vvent to your main line at the toilet you will stop this. Check to make sure your vents are not clogged by a bird or bees nest first.
They gurgle because of the sudden release of air. You have this gurgle because your vent pipes are either stopped up, in the wrong place, or are iadequate in size. When you drain water the you put pressure on the air in the drain lines. This pressure is actually sewage gas and should go out through your vent stack(s). You will need to repair or reppace your vents for this problem to be corrected.
standard size for bathroom sink drain is 1-1/4 standard size for kitchen sink drain is 1-1/2
1-1/4" is typically the diameter of a bathroom lavatory drain pipe. 1-1/2" is more commonly the drain pipe size in kitchen sinks.
OF COURSE