Marine Toilet Maintenance Tips


Early in the sailing season, the things we overlooked during winter storage can come back to haunt us. And with regard to our boat’s sanitation system, the spooky item is usually the marine toilet. Seals are often the first to go, with telltale waterlines dripping from the pump body. Less obvious are failures at the joker valve, the duck-billed rubber valve that prevents flushed water (and odor) from returning to the bowl. If you can’t completely flush your marine toilet, the joker valve may be failing.

Age and cold can cause the valve to grow stiff, but another cause of damage is caused by the addition of chemicals that can hasten the valve’s demise. Back in 2013, we tested joker valves for durability and flexibility and noted that some brands were clearly better than others. Conveniently, we also found that some brands of valves were interchangeable. (Although the manufacturers recommend against swapping, we did it, and it works).

In addition to our comments on each joker valve, we made some interesting ground-breaking observations on the effects of chemicals that are often introduced to marine heads. The results of our test busted more than a few head-maintenance myths.

joker valves
From left, the joker valves from Jabsco, Groco, and Raritan. Our joker valve test appeared in the July 2013 issue of Practical Sailor.

Ethylene glycol: As a result of our experiments, we recommend using ethylene glycol instead of propylene glycol anywhere human toxicity is not a concern. Black-water systems are fine, but avoid introducing ethylene glycol to the environment.

Propylene glycol: Propylene glycol dramatically stiffens neoprene, although you can soften the effected neoprene some by soaking it in water. Propylene glycol is not good for Jabsco joker valves and is bad for flexible neoprene impellers, particularly engine raw-water impellers. Several experienced mechanics we spoke with were convinced that winter storage in propylene glycol ruins impellers. Ethylene glycol is a better choice for engines and black-water systems, and draining may be a better approach to winterizing potable water systems. The propylene glycol severely crazed nylon strainers in our tests.

Methanol Windshield De-icer: De-icers did not cause any damage to our sample joker valves, but we don’t recommend them because of the risk they pose to other materials in the system.

Oils: While olive oil proved harmless to all test valves, corn oil caused some minor swelling, and baby oil caused the Jabsco valves to swell and soften. The Groco and Raritan nitrile valves were unaffected.

Urine: Urine was the most damaging off all the chemicals tested, inducing minor leaks in the Raritan valve. The fix is obvious: Flush the waste clear to the tank.

Acids, including Vinegar: We soaked the valves in diluted CLR, Lime-Away (sulfamic acid cleaner), vinegar, and 3-percent hydrochloric acid (diluted to 1 percent HCl) for a month. Vinegar caused minor and apparently harmless swelling in the neoprene valve, but not the nitrile valves. CLR caused significantly less swelling than vinegar and removed the lime several times faster, with less residue. Lime-Away damaged the nitrile valve, so don’t use this product in marine heads. Hydrochloric acid works fast and did not damage the rubber, but it is nasty to work with and its difficult to judge the dosage. Acid cleaning did not restore resiliency lost in the Raritan valve due to urine exposure. We recommend only CLR for acid cleaning.

Regarding regular treatment with vinegar, conventional wisdom is that white vinegar helps with scale. However, PS testing  shows it works too slowly to be ineffective, and that it is rough on rubber parts and metals in the process (see “Clean Potty Overkill,PS October 2019). Other acids remove lime faster with less collateral damage, so we’re crossing white vinegar off the list, classifying it instead as a potentially damaging myth.

Head treatments: We tried several of the most aggressive old-school blue treatments (Aqua-Kem and West Marine Max Control) and noted no important effects, although the alkalinity caused some minor stiffening of nitrile. We see no problem with using these, if the treatment is flushed through as directed.

Ammonia: Ammonia caused similar stiffening and loss in material resiliency that we saw with urine, but without the scale formation. We also can’t think of any good reason to use it.

Bleach: Bleach did no harm to components, but we do not recommend using it. It is bad for the holding tank bio-organisms and is incompatible with many holding-tank treatments.

Lysol Toilet Cleaner: We saw slight swelling in the valves after they were exposed to the Lysol cleaner, but nothing serious. Not recommended.

Grease: We tested valve compatibility with trailer bearing grease, Super Lube Synthetic grease, and Ideal Silicone Dielectric grease. The wheel bearing grease caused some minor swelling in the Jabsco valve. The other products had no effect.

If you’re in the market for a new head, check out comprehensive series of tests, beginning in with our two-part review of electric flush toilets February 2011. For a comparison of our two most popular manual flush toilets see “Two Marine Toilets go Head to Head.”  For a comprehensive discussion of your boat’s sanitation system as a whole, including our time-tested remedy for head odors, see our comprehensive eBook, Marine Sanitation: Complete Series.


Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 45 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida.


  1. Several years ago a representative for one of the manufacturers recommended adding a few drops of Marvel Mystery Oil into the toilet bowl from time to time to lubricate the pump and valves. Have you ever heard this, and is it satisfactory?

  2. If in the market for a new head please investigate the Lavac. It has a history of great reviews here and I have had excellent luck with it for the past seven years (although that probably ended with writing this note).

  3. La Vac. Ablsolutely the best, most maintenance free head in existence.
    If you don’t like working on heads, get a LaVac.
    I was in the crewed charter business with the boat that my wife and I lived aboard for more than 8 yrs. This head just keeps going, through thick and thin (literally). Charter guests will put the craziest things down a head. In the eight years that I had that head, I never once had to rebuild it. Never once had any significant repair. Just had to clear the occasional foreign object. Tampons, the simi-cloth handi-wipes. (This head would even pass Bounty paper towels ) And with this head that was a super easy job of unscrewing the quick release cap and clearing it. About a one minute job. That’s all I did in 8 years!! About onece a month I would flush some white vinegar through it. Never once had to clear or replace the exhaust output hose. A complete rebuild and pounding, clearing the output plumbing, (or replacement ) was at least an annual job with a regular head. And this is not a freak situation. When I bought my next boat, one of my first projects was to install a new La Vac head! Owned this boat for 6.5 yrs and again, never once had to rebuild or repaint the head.

    This all applies to a raw water flushed head, for long range full time cruising, For less intense and more occasional use where there is always plenty of fresh water, that will be an advantage in any head.

  4. I’ve been reading the blog posts and have seen lots of dialog regarding cleaning and odor….but nothing on the use or recommendations for lubricants in the manual pumping heads.

    Is there a recommended liquid for occasional lubrication of the head/pump?


  5. Next time you test, can you please add vinegar to the cleaning treatments? It seems pretty effective when I use it, but of course my personal experience is not science. Thanks!

  6. I have 2 Jabsco electric heads with seawater flush. I had trouble with one not getting enough water so I put a repair kit in it which made no difference. I took it back apart and noticed the impeller housing was worn. I ordered and installed a new housing and it worked like new.


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