What can I pour down a drain to unclog it?

August 25, 2024 6:57 PM

Recently, the drain in my bathroom hand basin has started draining slowly. (It does eventually drain fully over time.) There is no visible hair or other blockage in the basin. What can I pour down the drain to help unclog it?

I suspect the culprit might be a build up of residue from liquid hand soap; mouth wash; and toothpaste.

I want to avoid a plumber due to COVID risk and money.

For what it's worth, the shower in the bathroom is draining normally, and a nearby toilet is flushing normally.

I am in Australia.

posted by chariot pulled by cassowaries to Home & Garden (28 answers total)

Try pouring boiling water.
posted by dianeF at 7:03 PM on August 25 [5 favorites]

Boiling water I think is generally safe no matter what, unlike declog chemicals.

Drain Weasel (which it looks like you have a version of) is my go-to physical implement for pulling out clogs in bathroom sinks. A small plunger can help loosen them as well.
posted by supercres at 7:04 PM on August 25

I can't speak to what you get in Australia or what your options are, but when I had to call a plumber to de-clog my sink, they told me to get Talon drain opener. Literally that's what the plumber uses.
posted by jenfullmoon at 7:15 PM on August 25

When this happened to my bathroom sink drain, the fix was actually taking out the p-trap under the sink (quite simple in my setup, likely yours as well, a not-too-tight screw at each end) and cleaning the yuck out of the pipe from underneath. Worth trying?
posted by humbug at 7:22 PM on August 25 [8 favorites]

I use Green Gobbler drain clog dissolver, but it looks like it may be currently unavailable in Australia.

An alternative, if you can remove the drain cover: Take a cheap wire coat hanger, untwist the part that's twisted together, and straighten it out to make a stiff straight wire at least 30-50 cm long. Bend the tip (maybe 1 to 1.5cm) of the end back to make a small hook. Use this to dredge around in the drain. You may be able to pull up some slimy blobs of hair held together with sludge. Most of our slow-draining bathroom sink issues have been resolvable by 'hooking the drain' in this manner. If there are no blobs of hair (conceivable if you are bald and do not have furry pets), this approach may still be able to knock loose some blobs of residue from the sides of the drain.

Note, do not force a 'drain snake' down the drain; this is how we knocked a hole clean through the U-bend of our previous bathroom sink drain. It was not a fun situation.
posted by heatherlogan at 7:24 PM on August 25 [5 favorites]

Start with couple tablespoons of baking powder rinsed down the drain with about 1 cup of white vinegar, then close the drain stopper and leave for 10-15 minutes. Open drain stopper and pour a pot full of boiling water down the drain. If that doesn't work, I second humbug.
posted by Scout405 at 7:30 PM on August 25 [5 favorites]

^seconding Scout405. Or, in a similar fashion - if you have bottle-cleaning or denture-cleaning type tablets in the house, chucking a few down the drain can help dissolve the toothpaste/liquid soap gunk. A bit of water so they dissolve and fizz, then a couple of kettles of boiling water an hour later. Vinegar or denture cleaner + hot water aren't terrible, but please use eye protection and wear gloves anyway.
posted by Iris Gambol at 7:54 PM on August 25

I have had good success with tipping a cup of white vinegar down the drain, leaving it for an hour, then using a plunger to loosen things up.
posted by i_am_joe's_spleen at 7:57 PM on August 25

When my handbasin drain clogs, it does that because it's grown so many layers of biofilm that no chemical I've tried will reliably deal with it.

What does reliably deal with it is a hook made from a wire coat hanger. I gently unwind the hook from the twist that closes the body of the hanger, leaving me with a long bent wire that has the hook on one end and the remains of the twist on the other. I straighten out the hanger body, then bend the remains of the twist back onto the wire to make a narrow and wriggly hook maybe 40mm long and 10mm wide.

I use that to hoik out the drain grate, which in theory is supposed to just sit down in there but in practice is always well glued in with biological godknowswhat. Having got the top of the drain fully open, I then feed the hook down until it stops at the bottom of the P trap. A bit of gentle twisting and feeling about is usually enough to lodge the hook securely into the hideous living drain liner, which then pulls up in one or two completely disgusting black jellied floppy stinking pieces. Have a bucket handy to dump those in.

The process is like clearing the wax from Hell's own ear canal: beyond gross but oddly satisfying. And it opens the drain well enough that the two followup kettle-fulls of boiling water actually run down it instead of just sitting in the basin and mocking me with little burps.
posted by flabdablet at 8:08 PM on August 25 [10 favorites]

You did say there's no visible hair or clog but it could very easily be just out of sight. Folks have suggested a wire hanger, and I used one for a while, but you can get drain declogging things with a bunch of hooks on them for a couple bucks at any hardware store. They save you the trouble of fishing around to get at that thing - you stick that sucker in there and it bends right around the trap, and when you bring it back up it snags everything. Totally reusable too.

Once you've got the big chunks out, the natural remedies mentioned above are definitely worth doing - baking soda and vinegar and then boiling water. If it doesn't drain quick after all that, you'll probably have to remove the trap and get in there.
posted by BlackLeotardFront at 8:16 PM on August 25 [7 favorites]

Boiling water or vinegar might help for a little while, but I agree with humbug that manually opening up the p-trap and cleaning it out is likely to be the real solution. This isn't a big deal — p-traps are made to be opened, for exactly this reason. You don't usually even needs any tools. It's really simpler just to open it up and clean it out than to start shoving things down the drain or using harsh chemicals.
posted by ssg at 8:17 PM on August 25

If you do take the trap apart, don't make the n00b errors of (a) doing so without a bucket sat underneath it or (b) reflexively using the handbasin's own hot water tap to rinse it out. I've done both. Neither ends well.
posted by flabdablet at 8:32 PM on August 25 [16 favorites]

Since what we do is NOT a direct answer to your "pour" question I will make it short. You can buy long very thin brushes that are used to clean non-disposable straws. Brush at the end, and a hoop at the top. We attach a key ring to the top (to keep hold of the brush) and then poke around the drain with the brush end... we get loads of disgusting hair and other stuff out. We clean it up with a paper towel and trash it. Then run hot water and we're good to go for a month or two.
posted by forthright at 8:33 PM on August 25 [1 favorite]

Plunger first, then plunge again with hot water between every other treatment you may try.
posted by SaltySalticid at 8:35 PM on August 25 [3 favorites]

When I tried pouring boiling water down my drain, the porcelain of the sink cracked, so I'd avoid that unless you slowly bring it up to temperature first. The plastic strips with a bunch of hooks that BlackLeotardFront mentioned works really well in most cases though.
posted by willnot at 9:07 PM on August 25 [1 favorite]

1. Pour in a generous amount of vinegar and baking soda. Let it sit for a while. It will bubble up in a pleasing way.

2. After that's settled down, pour in a generous amount of Dawn or other standard (ie not "all natural" or whatever) dish soap. This will break up any fatty or oily elements of the clog. Let that sit for 10 minutes or so.

3. Pour in a pot or kettle or two of boiling water and see how you do. Repeat until it's all clear.

I've used this combination on sinks, toilets, and shower drains and it works remarkably well. I have a strong aversion to plunging and snakes and bringing up clods of hair and things, and so far this has seemed to dissolve whatever needs to be dissolved. You can also add bleach to the mix, but I'd do that sparingly and after any of the vinegar solution has dissipated.
posted by knotty knots at 11:08 PM on August 25 [1 favorite]

It will bubble up in a pleasing way.

It will indeed, and in so doing it will destroy some to all of the acidity of the vinegar as well as some to all of the alkalinity of the baking soda, making both of them less likely to act on the accumulated gunk in any meaningful way. The gas in those bubbles is carbon dioxide which has basically no effect on bacterial biofilms, unlike the oxygen produced by the similar-sounding fizz obtainable by dumping hydrogen peroxide down a drain.

Acidity is good for discouraging bacterial and fungal growth, and alkalinity is good for saponifying fats. Apply both at the same time and they cancel out and achieve very little. So enjoy your foam and fizz if it pleases you, but if you actually want to wield either vinegar or baking soda against a drain clog, chemistry says you'd get better results from using them separately.

Sodium hydroxide (caustic soda) is a much stronger alkali than either sodium bicarbonate (baking soda) or sodium carbonate (washing soda) and correspondingly rips into both fats and biofilms much faster, which is exactly why it's almost always the main ingredient in commercial drain cleaners. But it also rips into zinc, which is one of the elements alloyed to make brass, so if your drainage works include any brass fittings it will degrade those. Almost all Australian drains fitted in the last fifty years will be PVC for the main drain lines and polypropylene for the under-sink P traps, and caustic soda won't hurt those.

The main thing that renders a lot of chemical approaches fairly ineffective against handbasin clogs is that these most often consist of hair-reinforced biofilms that build up on the entire length of the riser between the bottom of the P trap and the drain hole in the basin, and it's hard to persuade chemicals to stay in contact with them long enough to make serious inroads. To do it properly you'd need to block the drain below the P trap so that the whole thing fills with caustic and stays filled for an hour or two, which is usually more trouble than mechanical cleaning methods anyway. A typical chemical clean will make only quite a small passage through a clog, which will then close up again fairly quickly. Physical gunk removal needs repeating much less often; I do our handbasin about every five years.
posted by flabdablet at 1:20 AM on August 26 [12 favorites]

For what it's worth, the shower in the bathroom is draining normally, and a nearby toilet is flushing normally.

That is indeed worth knowing, because it says that blocked vents are not your issue, leaving a straightforward buildup of accumulated drain gunk as the most likely cause.
posted by flabdablet at 1:27 AM on August 26 [2 favorites]

In my experience, the 'natural' chemical remedies do not work very well on my particular combination of hard water, soaps, tooth paste and hair.....so I always keep a bottle of drain cleaner on hand and use that as directed on the bottle. Most of them seem to rely on the same combination of chemicals and similar concentrations.

Depending on how much buildup you're dealing with, you may need more than one application and may also want to leave it working several hrs or over night, not just the hr or whatever the bottle says.
posted by koahiatamadl at 5:27 AM on August 26

Your hardware store may sell things similar to that described by forthright, and advertized to remove hair.
posted by SemiSalt at 5:29 AM on August 26 [1 favorite]

One of those plastic drain cleaner things, I guess they are called 'hair snakes' if you google them - will clean your p-trap and that's where most stuff gets stuck -works better than any chemicals.

I've never had any luck with chemical drain cleaners.

Do it twice a year or so.
posted by The_Vegetables at 8:05 AM on August 26 [1 favorite]

You can make one of the plastic drain cleaner thingies by notching the edges of a big zip tie.

We have found the enzymatic clearers slow on established clogs, but diligently using them with a 12-hour soak on each vulnerable drain once a month has seriously reduced clog problems in our longhair household.
posted by clew at 8:30 AM on August 26

I have regular drain issues (poor installation by a previous owner, has not risen to the top of the "things I have to spend a lot of money to fix" list yet), so I've tried nearly everything in the past. What has worked best for me is to pour several good-sized glugs of blue Dawn dishwashing liquid (not sure if they have this in Australia, but it is a magical substance) down the drain, wait 20 minutes, follow with a kettle of boiling water, and then run the tap on hot for a minute or so to finish up. I now do this monthly on the drains in question (bathroom sink and tub) which seems to keep them in good order.

Just be careful when you are pouring the hot water down the drain, sometimes it geysers up if you go too fast.
posted by Preserver at 10:06 AM on August 26 [1 favorite]

If the p trap is modern PVC, I vote for take it apart and scrub it out with brushes (ew...). If it's not all plastic, there is risk of it breaking when you try to take it apart, and I vote for a combo of the spiky drain cleaners like a Zip It or Drain Weasel, and brushes as far as you can reach.

Flabdabet is 100% with it on any liquid you pour down a slow drain will drain slowly but also too fast to do meaningful good.
posted by advicepig at 2:14 PM on August 26

My basement toilet was recently clogged with a slow drain for over a week despite frequent and vigorous plunging. I finally poured a decent quantity of dish soap down there, filled it and let it sit for an hour or so. The next plunge got it unclogged with minimal fuss.
posted by mikesch at 2:35 PM on August 26

Are you on a septic system or town sewer? If septic, you have to be a little careful with what chemicals you put down - I use this stuff and it's unclogged my vanity sink beautifully when I couldn't get a drain snake down it. Bonus is that it's not a smelly or caustic chemical so it can be used (and stored under the sink) without worrying that kids or pets might get into it. Just pour a dose in last thing at night, run a little water to get it down into the P-trap and let it sit there and digest all the mess.
posted by ninazer0 at 3:43 PM on August 26 [1 favorite]

In Australia (which is vast! so I hope this is applicable to your area), Dawn dishwashing liquid (handy for laundry stains, I can attest; other budget-friendly uses) appears to be sold at Woolworth, Costco, Solly's, & on Amazon.com.au.
posted by Iris Gambol at 4:09 PM on August 26 [1 favorite]

A visiting plumber recommended this Bio-Clean. It has bacteria and enzymes that will gradually eat & dissolve the various grease & scum that accumulates inside drain pipes.

It doesn't work instantly but over time it will clear up the pipes better than even roto-rootering in many cases.

You would put it in say every night for a week, then every week for a month or two, then every month or so.

I don't see that exact thing in Australia but this is quite similar and in general anything with bacteria, enzymes etc designed to clean drain pipes.

In the short term, as others have said, the immediate major stoppage is almost certainly in the drain elbow immediately below the sink - often right in the cupboard below. If you clean that out somehow you'll get 2X or better drainage immediately.

This is often called a P-Trap or S-Trap - you can google videos about how to clean it. Often you can do it with a bare minimum of tools or perhaps none. Sample video.
posted by flug at 2:11 PM on August 27