Composting toilets, do they actually work?

[Orrjames]

I want to redo our head system and if a composting toilet is actually worth a crap I might try it. Get rid of the smelly holding tank and all of it's parts. Whats' the buzz about them?

[SURV69]

They sound like a real alternative if you don't include the urine and if you ... ahem... not always full of sh-t.

It appears that once or twice daily would be a perfect marriage for a composter.

[skipmac]

Consensus opinion from most cruisers that own one is that they work quite well. However like everything there are trade-offs. Don't have one myself but as I understand it, you have to periodically remove the liquid waste and carry it to pour out somewhere. Plus there is the occasional disposal of the solids and replacement of the dry media.

I am planning a good bit of sailing and I think it would make more sense for me to have a system that will just pump directly overboard when off shore.

[Tellie]

I've had one for about three years now. One of the best moves I've made on my boat. Once you get the admirals "Are you outta your mind" issue resolved it's a great system, and yes the boat no longer stinks.
Skipmac, what's the difference between dumping a holding tank off shore and dumping a composter off shore?

[Orrjames]

Yes we are planning a long voyage ourselves and have a system in place. I may just get a new tank, hoses and macerator and call it done. You have a Pearson 422? Nice boat, is it a ketch like our 365?

[Mike OReilly]

Funny ... I'm just heading down to the boat to begin the install of our new Nature's Head.

A quick search here on CF will turn up a number of threads. My conclusion, after reading lots and talking to a number of local owners, is that they can work very well for a small crew. Proper installation, including the venting, seems to be vital, but if done right most users report zero odour.

Obviously the way they are used (including how they are emptied) is different than a standard marine head. As with all things, it's a trade off. I fully expect the benefits to far outweigh the negatives.

... but I'll let you know in September after our first season with it.

[Freerider]

I recently ripped out our old system and I'm planning to go with a composting head. The extra storage space i gained is worth it alone. Plus there's 2 thru-hulls that i can glass over and not have to worry about.

I'm excited to have a boat that doesn't smell like liquid sewage.

[Kettlewell]

Been using an AirHead since 2005--will never go back. Works as advertised. Offshore dumping can be problematic as it is a bit involved to empty and clean out, and not so easy to do if the boat is rockin' and rollin'. Luckily, it is rare to get to the point that it "must be done now," like can happen with a holding tank. You have plenty of warning and can therefore plan ahead for a calm day and well offshore. I have found that industrial-strength trash bags, found at places like Home Depot, can be used to safely store the material until dumping is possible, but I can see that the heads using standard 5-gallon buckets and lids could have certain advantages. One great advantage is that you can leave the thing over the winter--the more time the better--even using it while the boat is hauled out, and then dump in the spring. And, it really does keep the boat smelling good. I leave the door to the head propped open so the exhaust fan pulls air through the entire boat when we are not there. The current fan has been running 24/7 since 2007--I have it wired into the same circuit as the bilge pumps so that it is always on.

[nautical62]

I've had a traditional marine head, a composting toilet and an RV-style head. I feel each has pluses and minuses and how those play out depends on use.

I used the nature's head compositing toilet on a small trailerable trimaran I used in part for the Great Lakes. In that situation dumping overboard was not an option and being a small trimaran, the weight and volume of a large holding tank were impractical, so there the composting toilet seemed a great fit. It did require wiring in a small fan. Since my cruises were fairly short, I could just leave the compost to finish composting with no need to find a place dispose of partially composted waste.

For island and ocean cruising however, I prefer a traditional marine head with a gravity feed holding tank system. It's less expensive than the nature's head composing toilet. Rather than having to haul out and dispose of compost, some of which may not be finished composting, I just open a valve and the tank empties by gravity - no need to carry peat moss, or have any electrical components. Most boats are are designed with traditional heads in mind as well.

I think everyone faces different situations, has different boat constraints and different attitudes towards the trade-offs, so I don't think there's any universal answer to which system is best.

[jstevens]

I installed an Airhead in 2008 and have been using it as a live aboard since then with one winter at anchor in the Bahamas. I would never go back.
A conventional marine toilet that discharges overboard or a holding tank that pumps overboard, would be more convenient on an ocean passage as you don't have to carry the compost bin into the cockpit and dump it overboard. That is, move convenient until the marine toilet packs in. Having the sewage line become clogged halfway from Bermuda to the Chesapeake and having to take the entire system apart to clear it was my motivation to go to the Airhead.

John

[skipmac]

Originally Posted by Tellie

Skipmac, what's the difference between dumping a holding tank off shore and dumping a composter off shore?

It's not the environmental issues of regular vs composted waste.

Regular head to dump you just pump the head, waste all gone. Composting head you have to physically carry out a bottle or container of waste.

Since you have one, how often do you have to carry out liquids to dump? How frequently for solids?

[skipmac]

Originally Posted by nautical62

For island and ocean cruising however, I prefer a traditional marine head with a gravity feed holding tank system. It's less expensive than the nature's head composing toilet. Rather than having to haul out and dispose of compost, some of which may not be finished composting, I just open a valve and the tank empties by gravity - no need to carry peat moss, or have any electrical components. Most boats are are designed with traditional heads in mind as well.

Exactly my logic for sticking with a traditional head. Glad to hear someone with experience with all types of heads made the same decision as mine was based strictly on what I read on CF.

[Kettlewell]

For island and ocean cruising however, I prefer a traditional marine head with a gravity feed holding tank system. It's less expensive than the nature's head composing toilet. Rather than having to haul out and dispose of compost, some of which may not be finished composting, I just open a valve and the tank empties by gravity - no need to carry peat moss, or have any electrical components.

How did you rig up a "gravity feed holding tank system?" It is an interesting idea I have also thought about, but on several boats I could not figure out a way to make it work--always ended up with the necessity of a pump. Also, not sure about total cost, once you figure in the toilet, pump, hoses, holding tank, through hulls, y-valve, hose clamps, etc.

On the "island and ocean cruising thing," that is where the composting head truly shines. You can spend a lot longer in a pristine harbor before needing to empty things--we found 4 people could go a month before emptying it. I've never had a holding tank that was good for more than a couple of days. Sure, on ocean passages sending the effluent overboard is easy, but not so great in beautiful cruising grounds with no pumpout facilities. Whereas closer to home there are numerous pumpout stations and also access to parts and supplies when you need to fix something--one of the great benefits of a composter is that there is nothing that can break that you can't fix with the simplest of tools, or jerry rig, all without having to deal with a huge stinky mess.

[nautical62]

Originally Posted by Kettlewell

How did you rig up a "gravity feed holding tank system?"

I installed one on my Hunter, by placing a tank just above water line under the vanity counter. I placed the out take on the bottom with the inspecting port directly above, so it could easily be snaked if ever needed (which it didn't). I like the bottom of the holding tank just above waterline so when sailing water will be forced up in and drain out, offering some cleaning action.

My Moorings boat and most Moorings boats I've traded on also had gravity feed systems, much like the above, and I've never noticed any smell on any of them. I prefer having the through hull under the vanity - makes it easy to access. (some were put on the bottom of the cockpit lazarette - not see easy access)

Originally Posted by Kettlewell

Also, not sure about total cost, once you figure in the toilet, pump, hoses, holding tank, through hulls, y-valve, hose clamps, etc.

Well for me, I had a holding tank with both systems anyways - not wanting to empty a urine container manually daily, I installed a small holding tank for my airhead composting toilet. I placed it directly under the floor so it was a straight, short gravity drain to the tank. So the plumbing was similar, but my marine toilet was under $200 compared to about $900 for the airhead. I also had to purchase and install a vent system for the airhead, including dorade vent in my case. In my case, installing the airhead system was much more expensive than when I installed a traditional marine head with gravity feed. Obviously there are choices to be made with both options that can affect overall costs and comparative costs.

No y-valve or waste pump needed on a gravity feed system. Just open the through hull to drain, leave it shut to hold. (Can use a T for pump out option if desired)

Originally Posted by Kettlewell

You can spend a lot longer in a pristine harbor before needing to empty things--we found 4 people could go a month before emptying it.

True and I think that's a great example of how where one cruises and what lifestyle one has can affect which system makes more sense. I agree that composting toilets really make sense when one can't dump overboard frequently. I tend to cruise in places and in a way, where it's easy and appropriate do dump at least every other day, so holding simply isn't an issue. It's a different story for people who like to stay put in harbor, cruise lakes, or for other reasons can not dump frequently.

That's exactly why I think each person should evaluate their own cruising area, boat, lifestyle and temperament when deciding which system is best for them. The system that I prefer for my cruising lifestyle may not be the best choice for someone else, given their circumstances.

[thinwater]

There are also those that ripped out brand new composting heads they installed went back to holding tank systems. Beware of owner bias in threads.

Comparing old, poorly maintained heads to new composting systems is also invalid. Visit a boat with a good holding tank system and its existence will be without evidence.