5 ways to clear a slow or stopped drain on a boat -- without any dangerous chemicals.

Slow or Stopped Galley Drain

Living on a boat, you’re not going to use Drano on a slow galley sink drain — or one that’s totally stopped.  So what do you try?

I’m assuming here that the sink drain has worked well in the past, so it’s not an “engineering” problem like too small a drain hose or location problem.  Those are issues way beyond the scope of this article!

Dave and I always believe in trying the simplest fixes first:

  1. Seacock. Assuming that the seacock for the drain is in the bottom of a locker, it’s possible that something fell against it and partially closed it.  Unlikely, yes, but possible.  And you’d feel really silly if you hadn’t checked the seacock first — it’ll only take a minute or so.  With most valves, when the handle is in line with the hose, it’s fully open.  And while you’re at it, work the seacock some — it’s a good maintenance precaution so it doesn’t freeze in one position, and maybe the blockage was right in the valve and this will dislodge it.
  2. Plunger. If you have a plunger on board, try it first.  Note that a plunger won’t work unless the basin is full of water — air will just compress and you won’t create any pressure to dislodge a blockage.
  3. Hot Water. Grease and soap are the most likely culprits for a slow drain.  Hot water will dissolve either one.  Boil a teakettle full of water, and pour it down all at once — don’t trickle it in.  You should see improvement after one pan, although it may take two or three to fully restore the flow.  If it doesn’t, you’ll have to try the next step.
  4. “Drain Cleaner.” You don’t want to use any harsh chemicals both for the sake of your drain hose and for the environment.  But you can use a couple of everyday items and simple chemistry to create a safe foaming drain cleaner.  Pour 1/2 cup or more of baking soda down the drain, then add 1 cup of vinegar — cider vinegar works best as it has the highest acidic content.  It’s a simple, mild acid-base combination that will foam and expand and work its way through a lot of clogs.  For even better results, if you have a drain plug or stopper (even a rag is better than nothing), immediately put it in the drain hole and hold it in place so that the soda and vinegar mix expands down the hose and not just up into the sink.  Let it sit 10 to 15 minutes, then pour another pan of hot water down. UPDATE: Read about a great drain cleaner that’s environmentally friendly for use on boats:  Super Digest-It and Marine Digest-It for head and holding tank problems.
  5. Thru-Hull. If the above hasn’t cleared the problem, the next step is to clear the thru-hull.  And that means going overboard with a mask, snorkel and large screwdriver (and any other dive gear that might be appropriate for the conditions).  I like to wear a pair of old jersey gloves to protect my hands, too.  Basically, you need to carefully stick the screwdriver into the thru-hull and scrape out any barnacles or other things that may be lodged in there.  After grease and soap, this is the most likely cause of problems.
  6. Hose. When all else fails, you’re going to have to remove the hose, check for blockages and if you can’t remove them, replace the hoses.  Be sure to close the seacock before beginning the work!  A wire coat hanger or piece of 1/4″ dowel can work wonders for clearing blockages.
A friend recently told us about another way to clear a nasty drain without chemicals.  It’s called a Zip-It and it’s basically a 17″ wand with little teeth on it.  Stick it down the drain and pull it out, and it grabs all the nasties and pulls them out too.  Officially, it’s “disposable” but can usually be used a couple of times before being too bent up.  I got one and have used it a few times, particularly on cockpit drains, and it works great.

While I titled this article as being solutions to a slow or stopped galley drain as this site deals with galley issues, the reality is that the same techniques work on the head and shower drains as well.

Here’s hoping that you never have to use this information, and that if you do, the problem is quickly solved!

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  • Tasha Hacker
    Posted at 19 January 2013 Reply

    Oh my goodness, thanks for this posting! We’ve had a sink drain problem for months now and I found your site while Googling solutions. I’ve done the hot water, and now I”m on the soda and vinegar. Fingers crossed!

  • Helen
    Posted at 30 May 2013 Reply

    Baking soda, vinegar and then pour boiling water in the drain..that will most clogs…may need to repeat one more time

  • Marta Crichlow on Facebook
    Posted at 30 May 2013 Reply

    The Zip It is a great idea for the boat, plastic: won’t rust into nothing and should not damage the hose! Thanks, again! Love your site and all the ideas.

  • Marta Crichlow on Facebook
    Posted at 30 May 2013 Reply

    The Zip It is a great idea for the boat, plastic: won’t rust into nothing and should not damage the hose! Thanks, again! Love your site and all the ideas.

  • Melody s/v Vacilando
    Posted at 30 May 2013 Reply

    Great stuff and I always try the vinegar and baking soda trick first, but we did find a product that worked wonders on a sink drain that just would not budge. It’s from a brand called Unique Natural Products and it WORKED. We now use it once every month or so – just close the seacocks and put a little down all of your drains and it will keep them draining like a charm. We wrote about their product here: http://www.mondovacilando.com/a-slippery-slope/ and no, we are not sponsored by them (yet). I just love their products because they are all natural and they work just as well if not better than some chemical laden products on the market.

  • Pieter Kommerij
    Posted at 30 May 2013 Reply

    Hi, Yes indeed a nasty subject. However, on board we try to avoid clogging sinks, by wiping the dishes and pans etc with a paper towel to get the grease and bits and pieces out first… (then and if possible, we wash with sea water and rinse with fresh). If the sink does get clogged, the trusty rubber plunger does the trick always.. So far no need for chemicals. Actualy we did that once in the heads… Muriatic acid seemed to be the answer to the problem.. it turned out it wasnt, and instead the ceramic bowl seems to be much easier to get stained after having flushed with this stuff.. (i wouldnt recomend the use of this type of acid). Thanks for posting all those handy things. Best rgds
    SV Onda Boa

  • Rebecca
    Posted at 28 August 2013 Reply

    Very timely link to this in your weekly newsletter…one of our toilets had been backing up, and the baking soda/vinegar seems to have cleared it right up! I always think about vinegar but totally forget baking soda!

  • Diane Cook
    Posted at 20 February 2014 Reply

    Boiling water now!!

  • Mark Redmond
    Posted at 20 February 2014 Reply

    I usually use a beer coozy as a plunger. Just cover the hole and push down into the drain – it usually works and I always have a coozy close by on my boat!

    • The Boat Galley
      Posted at 20 February 2014 Reply

      Had never heard of trying that. But it would mean that my beer might get warm :/

  • Taunya
    Posted at 11 August 2015 Reply

    Be careful with the plunger that it isn’t used on things that have valves like a joker valve… Ie your toilet… Or you’re creating more problems than you solve.

  • Lysa Stulberg Evans
    Posted at 11 August 2015 Reply

    I found this eco friendly stuff

    • The Boat Galley
      Posted at 11 August 2015 Reply

      I actually mention that in the post and they’ve done a couple of giveaways here 🙂 Good stuff!

  • The Boat Galley
    Posted at 11 August 2015 Reply

    Thanks for the compliment and for letting others know!

  • Donna Chiappini
    Posted at 11 August 2015 Reply

    Don’t laugh but we used our dinghy foot air pump to blow out our clog once. It worked wonders.

  • Charlotte Caldwell
    Posted at 03 August 2016 Reply

    We have a sink sieve in the galley sink and always use it (now!). A plum pit went down the drain when we were removing the sieve to clean it and the pit plugged up the drain resulting in us having to dismantle all the hose.

  • Russ Fink
    Posted at 03 August 2016 Reply

    We used a flexible hose which fit inside the drain hose to clear organic growth inside a slow sink drain in the head. It worked wonderfully.

  • Sherry Matas
    Posted at 03 August 2016 Reply

    Sink/drain strainer, sink sieve, whatever you want to call it… get one to stop all large particulate matter from going down the drain.
    Dishes and scraps go into a bag for disposal at sea outside 3 miles or land disposal.
    Grease goes into glass jars for re-use or land disposal. Never down the drain!

    Avoidance is easier than replacing the plumbing.

    • The Boat Galley
      Posted at 04 August 2016 Reply

      True, but sometimes things happen either by accident or guest. 🙂

  • Evan W
    Posted at 26 December 2016 Reply

    Yes, the dingy foot pump works wonders. Detach the sink hose from the sink (either scoop out residual water from the sink or use a bucket underneath. The dinghy hose is typically the same size as the sink hose, and some pumps have a “portable fitting” allowing you to adjust any difference in size. Once attached, simply standing on the pump should create enough pressure to blow anything through. Once cleared and reassembled, we’ll rinse out with boiling water. Have only needed to do this once in the 10 years I owned my previous boat (Catalina 30).

  • Jennifer Sampica
    Posted at 20 April 2017 Reply

    Thanks for the post, Carolyn! The Zipits are awesome, we’ve uses them at home AND the on our boats.

  • Rosalind Franks
    Posted at 20 April 2017 Reply

    I had never heard of a zipit. Many thanks

  • Helen Gimmy
    Posted at 28 August 2017 Reply

    We have a 2000 sharpe houseboat and the drain is stopped up on the upright pipe on top of the boat that drains rainwater.Is there a way to unstop it? Water sits on top of boat and makes the top turn awful color also is rmakiing the gel coat crack,

    • Carolyn Shearlock
      Posted at 29 August 2017 Reply

      There is most likely something in the pipe. I’d try the Zip-It — it works really well.

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