“Oh no, it’s poop again!”

While we probably have received the most inquiries about where our mast is, questions about our composting toilet are definitely number two. Hehe.

Replacing our traditional marine flush toilet and holding tank with a composting toilet was the first big boat project we did after purchasing our Tartan 37. We have been living with our composting toilet for a while now and have gotten a feel for pooping in a bucket so to speak, and would like to share with those who are curious about making the switch.

As with most decisions, we approached this one fairly methodically, however in full disclosure, there was one pretty major factor that influenced our decision:

We already owned the composting toilet.

We actually purchased the composting toilet (before buying our Tartan 37) to put into another boat we had under contract, because that boat had no toilet whatsoever, and the composting toilet was going to be the easiest/quickest to install. When that boat purchase fell apart we were left without a boat — but we had a brand new composting toilet!

Back to our decision making process…

One thing we loved about our Tartan was that she smelled amazingly good. No diesel odor, no mold or mildew, and the distinct odor of human waste — inescapable on many boats — was nonexistent. Much of this was due to the previous owners never using her as a full-time liveaboard. She was kept at a dock, sailed mostly on weekends and the occasional multi-week summer trip — all in FRESH WATER.  To top it all off, she was well-loved by her previous owners, who kept her in immaculate condition.

And we were about to change all of that completely. We planned to liveaboard, and saltwater was in our future.

During our shake down sail across lake Michigan, our plan was to figure out what worked and what didn’t. We wanted to figure out what we absolutely needed to change right away, and would go on the back burner for the future. Besides having a wonderful time Cruising Lake Michigan, we came back with a punch list of changes we wanted to make before traveling full-time.

At the top of that list was replacing our marine head and holding tank.

Why We Replaced our Marine Head with a Composting Toilet

We quickly realized that the only reason the head didn’t smell was because it wasn’t really being used. Once we started using it, that changed quickly. And the smell permeated everything. Even when you weren’t physically using the toilet at that very moment, the smell was there. It was disheartening.

During one rough passage, we went down below to see water backing up into the bathroom sink and the toilet bowl. My first thought was that water was coming up the thru-hull and filling them both up, since we were beating into some heavy winds and heeling over pretty good. I quickly remembered that we had a Y-valve under the sink that allowed fresh water to be pumped into the toilet from the sink, or raw water from the thru-hull; I figured it had been left in the wrong position allowing water from the lake to enter the boat through the sink and siphon down into the toilet. So I closed it, and went back up on deck.

Still being rather new to the boat, I thought I had solved the problem. Ten minutes later I went below to check up on the situation…


Now there was much more water in the toilet bowl and the sink than before and it was brownish in color and it was spilling out into the head pan with each wave we crashed into! All the reading I had done about disasters at sea and how to survive them did not prepare me for this one…this was a different kind of disaster I hadn’t imagined.

As many of you know, the joke was on us — our joker valve was bad — but it was exactly at that moment we knew we never wanted to deal with that situation again.  We pulled out the holding tank as soon as we got back to the dock.

Composting Toilets vs. Marine Head & Holding Tank

There are a number of benefits to replacing our marine head with a composting toilet, in addition to simply avoiding sewer water splashing about the boat:


  1. We can go longer between ‘removing’ our waste. We used to have a 12-gallon holding tank in the v-berth. This is pathetically small. The two of us together generate just over 1 gallon of liquid per day, then adding solids and the water required to flush, means we could go maybe 5 days between pump-outs — if we were lucky!?! We can go a good week and a half before needing to empty the composter — and this is using the smaller 3-gallon C-Head which we had to go with because of the smaller size of our bathroom/head.
  2. We reduced weight onboard. 12 gallons of liquid/solids is heavy! We didn’t like having all that weight at the pointy end of our boat.
  3. We opened up more storage space for other things. We gained a bunch of storage room under the v-berth, and completely opened up the previously unusable hanging closet aft of that once we removed all the massive hoses and plumbing that ran through it connecting the head to the holding tank.
  4. The smell literally disappeared. The only smells we have now are when we open the lid to the toilet, and to be honest it’s mostly the liquids that smell. (And a spritz of vinegar into the bowl helps with this.) The solids portion of the toilet is quite tolerable.
  5. We get to choose when to deal with emptying the waste. We don’t have to be back at a dock every few days to get a pump-out.
  6. We save money not paying for pump-outs.
  7. We save the precious fresh water that was once used to flush.
  8. We closed off an unnecessary thru-hull.
  9. There are almost no moving parts, almost nothing that could break, and next to NO maintenance — just cleaning.
  10. If anything does break, every single component can be easily sourced and fabricated anywhere in the world.  It’s literally a bucket with some PVC pipe inside.


  1. There is really only one negative. It shows itself a few different ways, and can be a big turn off for some: You will be physically more intimate with your solid waste. With a traditional marine head, you don’t really have to deal with it until something breaks, but then you’re really up close and personal with it.  You can pump a lever to flush it out of sight and into the holding tank. You then pay someone to pump it out of your boat and haul it away for you. Essentially once you’ve done your business you may never need to see it again. Unless of course, UNTIL SOMETHING BREAKS. And it will, at the worst time, in the worst place, and it won’t be pretty. With the composter, you’ll be dealing with it yourself on regular basis, but with much less drama. After you do your business you’ll need to cover it with a composting medium, then once the container is full you’ll empty it yourself. It doesn’t get flushed away, you won’t be paying someone to remove it. But — and it’s a huge BUT — doing so makes all the difference. Solid waste in the composter is so much more tolerable than the soupy sludge found in clogged marine toilets and holding tanks. So if you can get over the initial ick factor, it’s so totally worth it.

Thoughts on the C-Head

There are a number composting toilet options available: Nature’s Head, Airhead, and C-Head, to name a few.

They are all fundamentally the same device, and function in a very similar way:  they each separate solids from liquids, churn up the solids to keep them covered and empty when needed.

Each may perform these tasks in a slightly different manner, but choosing between the available options is likely to be based more on size and price than any available specific features.

We went with the C-Head and are quite happy with our decision. Besides being the smallest option (which was necessary to get it to fit next to the contour of the hull in our head) it was also the cheapest which was a nice bonus. And to top it all off, it was built by a sailor specifically for sailors. This becomes obvious in a few key areas we’ll point out below. The Nature’s Head seems to be marketed more towards off-grid living as a replacement for a normal household toilet, and the Airhead seems a little more RV-oriented.

The C-Head is dead simple, and aside from the faux teak which blends in nicely with the rest of our interior, the remaining parts and pieces could be sourced anywhere in the world, if there was ever a repair needed. The agitator is made out of common PVC pipe, the liquids container is a milk jug that can be replaced with any other milk jug at any time. And the solids container is literally a 3- or 5-gallon bucket. Minimalism and simplicity are awesome.

The other major advantage of the C-Head for us was the simplicity of cleaning and emptying. Remember this is the one big negative for composting heads — you have to deal with your waste yourself — so seeing as it’s just a 5-gallon bucket, it is incredibly easy to dispose of the waste, whether it’s over the side while offshore, or into a garbage bag when appropriate, hosing it down and bleaching it if need-be or dragging it through the saltwater, all makes quick work of the job when you want to get it cleaned up.

In Summary

Would we make the same decisions again if in a similar situation?  Yes, absolutely. We’re very happy with the composting toilet, and happy with our choice of a C-Head.

If we could design our perfect waste-disposal system, in our perfect boat?

It would be this: A composting toilet for in-shore business in one hull, and a traditional marine head (no holding tank) for going straight into sea while offshore in the other hull. Yup you read that right — two hulls. We can dream. 😉

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