Suds coming up other side of double kitchen sink
September 20, 2021 3:51 AM   Subscribe

We have a double kitchen sink. When soapy water drains out of the one side, suds appear on the other side of the sink. This happens on both sides. I suspect that it's coconut oil that was mistakenly poured down the drain and cooled. I have tried using baking soda, vinegar, and hot water to clear it out, but it is still happening. Is there anything else I should try before I call a professional? (I'm not very handy.)
posted by synecdoche to Home & Garden (19 answers total) 1 user marked this as a favorite
Response by poster: (I should add that water goes down the drain just fine.)
posted by synecdoche at 3:52 AM on September 20, 2021

I once had a double sink like that and had the same problem; the annoying bit is that the clog is probably further down the pipe, or it's settled at the point where the pipes from each drain meet, that your efforts just plain haven't reached yet.

I'd just keep at it - try hot water poured into both sides, and also try pouring it from a height (I would fill my kettle and bring it to a boil, and then hold the kettle at about shoulder level above the sink and aim my pour at the drain). It splashes a little, but it's got a bit of gravitational force behind it that drives it a little further down into the pipe.
posted by EmpressCallipygos at 3:56 AM on September 20, 2021 [2 favorites]

As long as it drains it's not worth calling a plumber. Have you tried using a plunger?
posted by mareli at 3:59 AM on September 20, 2021 [3 favorites]

You could also try a snake. If you own a home you’ll be glad you have one at some point. A 25 ft snake is in the neighborhood of $30 at Lowe’s or Home Depot.

Do you have a garbage disposal? Depending how your pipes are configured, you may need to start the snake below the disposal.
posted by fancyoats at 4:05 AM on September 20, 2021 [3 favorites]

Every double sink I've ever used has done that, in multiple apartments and houses. As long as it's draining, I wouldn't worry.
posted by ralan at 4:52 AM on September 20, 2021 [18 favorites]

Have you checked the trap and pipework under the sink? It's one of the simplest DIY tasks, on a level with changing a lightbulb or handing a picture.
posted by pipeski at 4:52 AM on September 20, 2021 [1 favorite]

...but yes, as long as it's emptying and not backing up, that does sound fairly normal.
posted by pipeski at 4:53 AM on September 20, 2021

Mine does the same thing. As far as I know, we haven't poured any oil down it. It seems to drain fine, so I'm not worried.
posted by kinddieserzeit at 5:02 AM on September 20, 2021 [1 favorite]

I have lived someplace with a double sink for 33 out of my 35 years of life and this has happened in every one of them. Look at your under sink plumbing connections. It's just the unbroken air filled suds bubbles rising to the surface via the path of least resistance. It's not a pathology.
posted by phunniemee at 5:37 AM on September 20, 2021 [7 favorites]

This is not operating as it ideally should but it's not a huge problem.

To use a plunger, you'll have to have the other side completely full and well plugged, and also maybe have a second person to hold the plug in. But a plunger is the least invasive and best way to go at this, after liberal bouts of boiling water in both sides at the same time.
posted by SaltySalticid at 5:56 AM on September 20, 2021

Phunniemee is right - while there could be a clog, this is normal behavior for suds and I wouldn't be concerned. It's irritating, but not symptomatic of any sink issues. Learning how to check a sink trap and manipulate a plumbing snake are useful things to do, though.
posted by fortitude25 at 6:57 AM on September 20, 2021

This is how my kitchen sink operates and has always operated.
posted by 41swans at 6:58 AM on September 20, 2021

I don't know that I would be concerned, but in my many years of living on my own with a double sink, I do not recall ever seeing this. If I have a lot of suds in one side and are rinsing them down the drain, they seem to get rinsed down after the bubbles collapse. Why would they suddenly reform? I get the air and water pressure could force them up the other side, but if they were dissolved in order to drain, why or how are they reconstituting?

Having said all that, if your sink drains and does not smell, it does not seem like a big worry.
posted by AugustWest at 8:17 AM on September 20, 2021

You could try plugging both sinks, filling them both with as much of the hottest water you can get as they will hold, then pulling both plugs at the same time. Measure the time it takes them to drain. Then do it again and measure the time again. If you get any speedup at all, then you're eroding some kind of fatty obstruction.

Even if you don't see a speedup from draining several double sinks full of hot water in quick succession, then as long as they're both draining about as fast as they always have, you've got no problem worth worrying about.
posted by flabdablet at 9:29 AM on September 20, 2021

I'd be careful of a plunger: P-traps (that U-shaped thing underneath your sink) are amazingly easy to blow off if you get a lot of downforce in your sink drain, and then you've got not only a larger repair job, you've got a big ol' mess.

This is what lye, or other drain clearing chemicals, were made for. I suspect you've got some fat and gunk in your P-trap, and something strongly alkali (and, yeah, baking soda is kinda alkali, but this isn't time to fuck around) would turn that into soap, and problem gone.
posted by straw at 9:32 AM on September 20, 2021 [1 favorite]

Response by poster: Thanks all. Nice to hear I shouldn't worry. It threw me, because I've never seen it happen before with these sinks.
posted by synecdoche at 1:36 PM on September 20, 2021

I'm lazy. If water goes down the drain just fine, as you say, I'd eat a PopTart and stop worrying about the suds.
posted by Doug Holland at 3:19 PM on September 20, 2021 [2 favorites]

Also, if all that "suds appear" means is that a bit of foam pushes up through the drain in the other tub, the most likely cause is using way too much dish soap.

To test this, try halving your usual quantity and see if the dishes still get clean as fast as you want them to. Keep doing that until they don't; that's what "not quite enough" looks like.
posted by flabdablet at 6:11 AM on September 21, 2021

Oh, and the most common cause for using too much dish soap is a muscle-memory squirt delivered from a bottle of a familiar brand that the manufacturer has quietly replaced with a more concentrated version.

In theory this is supposed to save consumers money and reduce waste. In practice, 2X concentrated detergents sell for almost twice the price and many - perhaps even most - people still use up bottles at about the same rate as always.
posted by flabdablet at 6:46 AM on September 21, 2021

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