Vinegar+baking soda+hot water+sink drain= hole in metal pipe??????
September 5, 2014 4:58 AM   Subscribe

The bathroom sink drain was clogged, probably with hair. The tenant poured some combination of baking soda, vinegar, and boiling water down it. Shortly afterward the bottom of the metal U-shaped drain pipe beneath the sink in the vanity cabinet developed a hole. The vanity full of useful and not-so-useful items was flooded. Could this combination of ingredients have caused the metal pipe to corrode. I don't know what kind of metal it is.
posted by mareli to Home & Garden (16 answers total) 3 users marked this as a favorite
Vinegar (acid) and baking soda (base) neutralize each other, so that's an odd combination to use (unless the tenant first used one, then later the other). I'd suspect that the metal pipe was very close to developing a leak anyway, so maybe the vinegar was the straw that broke the pipe's back.
posted by akk2014 at 5:13 AM on September 5, 2014 [2 favorites]

Yeah....alone that combination wouldn't cause that kind of damage. Odds are the metal was weak and corroded though but a buildup of soap/hair/and other drain stuff was keeping the water in the pipe until the hot water dissolved it away enough to let the water leak out.
posted by Captain_Science at 5:16 AM on September 5, 2014 [11 favorites]

No, old age is probably the cause of a failure like that.
posted by fritley at 5:21 AM on September 5, 2014 [4 favorites]

Drain volcanoes are a thing I learnt about from Unfuck Your Habitat. Their advice is that the boiling water might melt PVC pipes, but metal pipes should be okay (though they admit they're not plumbers).

I'd be surprised if that combo could cause damage to metal pipes, though.
posted by terretu at 5:27 AM on September 5, 2014 [3 favorites]

Baking soda, vinegar, and boiling (or very hot) water are all recommended because they are less corrosive than the alternative, Drano. (My reluctant preference is for a drain snake or Zipit, but I get why the tenant started with what they did.)

I think it's much more likely that the blockage requiring the drain volcano and the failure of the drain are related -- AKA the corrosion was contributing to the blockage, and eventually caused the drain failure as well. Or as Captain_Science notes, it may be that the blockage was also blocking a leak.
posted by pie ninja at 5:33 AM on September 5, 2014 [13 favorites]

Yeah, this baking soda-vinegar-and-hot water concoction is often recommended for old, easily-damaged pipes because it's gentler than other chemical techniques (although I think plumbers generally do prefer a snake). The pipe was probably already corroded.
posted by mskyle at 5:45 AM on September 5, 2014

I busted a hole in a (corroded) cast iron pipe with the air from hand-operated pneumatic plunger. It tends to clog at the joint where PVC meets cast iron, and I was pumping into a valve a few feet away from the breach. I was shocked because I didn't have a very good seal and was wondering if I would even move the clog. The pipe was very corroded obviously, but had been functioning fine.

I'm going to guess this was a similar effect-- but in this case it was CO2 from the reaction instead of air. It can take very little internal pressure to bust a corroded pipe-- it was going eventually regardless.
posted by Mayor Curley at 6:22 AM on September 5, 2014

It's possible that they first tried to dislodge the clog manually by poking a wire hanger down the drain or plunging, and that this is what breached the (already rusted) pipe. Most people don't go straight to baking soda and vinegar when the sink clogs.
posted by pullayup at 6:39 AM on September 5, 2014

If it is galvanized steel, those things corrode from the inside out, so it could have been corroding for a long time before your tenant use the drain volcano. You wouldn't see it rusting.

I always go straight for the volcano when my drains are slow, fwiw.
posted by girlpublisher at 7:22 AM on September 5, 2014 [2 favorites]

FWIW, the idea is to put baking soda and vinegar (in either order) so they bubble vigorously in hopes of dislodging the clog. Heat makes the reaction more vigorous. Neither chemical will corrode the pipe in any short period of time.
posted by SemiSalt at 8:32 AM on September 5, 2014 [2 favorites]

Galvanized steel has a relatively short lifespan as a plumbing material. Worse so if it's tied to brass fittings. This is a maintenance issue, not a tenant abuse issue.

Especially since plastic has been the U-trap material of choice for a lot longer than a reasonable working lifespan of galvanized steel for that same application.
posted by straw at 8:43 AM on September 5, 2014 [1 favorite]

I recently had to replace the sink trap under our kitchen sink, which I installed when we moved in ~13 years earlier. It was new pipe then, but simple usage had eaten it away from the inside to the point where the metal literally fell apart as I attempted to remove it. So...yeah, maintenance issue. Even if your pipes are T316 stainless, this stuff doesn't last forever.
posted by mosk at 9:44 AM on September 5, 2014

The clog was probably obscuring an existing weakness. Vinegar and baking soda fizz, which is sometimes useful for "fluffing" a clog, just getting it to budge a little so that water can flush it away. But it's not corrosive - you could mix it in your hand. It's way safer and gentler than Drano, for example, to both the plumbing (and any plumber that might have to deal with it afterwards) and the water supply.

I had a bathroom with one of those old galvanized pipes, and it failed when I bumped it with the sprayer of a bottle of cleaner, moving it around under the sink. It just disintegrated in silver-backed rust flakes - the pipes are thin to start with, and they rust from the inside.

So if you're looking for liability, no, they did not break your sink. It's likely if it hadn't gone so dramatically it would have slowly leaked into the back of the cabinet and the wall, doing all kinds of gruesome things nobody might notice for months or years, eventually necessitating a complete tear-out. (That's what the other bathroom in that house did.)
posted by Lyn Never at 10:03 AM on September 5, 2014 [2 favorites]

That pipe was a goner already.
posted by quince at 12:55 PM on September 5, 2014 [1 favorite]

Look at an old metal trap the wrong way and it will break. Vinegar and baking soda won't do it.

Their advice is that the boiling water might melt PVC pipes

I've tied PVC into cast iron pipe using a (molten) lead joint, so no, this is not in any way possible.
posted by hafehd at 5:52 PM on September 5, 2014 [1 favorite]

No, old age is probably the cause of a failure like that.

I am a tenant who broke a metal drain pipe in my unit by doing... nothing. We have town water that is treated with a small amount of what I think is chlorine and over time it just eats away at pipes. And by "over time" I mean I'd been living here for six years and the pipe which had probably been there for a few decades just gave way. I was unscrewing the nut-thing between them and the whole thing came off in my hands and was clearly nearly gone for quite some time before that.
posted by jessamyn at 7:28 PM on September 5, 2014 [1 favorite]

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