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composting toilet report

118K views 444 replies 97 participants last post by  MikeOReilly 
#1 · (Edited)
In a discussion of heads late in the spring I mentioned that I had installed them in my boat and a few people asked me to write up my experience with them, so here goes.

First a bit of background. I bought my J40, Genie, in the fall of 07 and began a lengthy refit. I had read on this site about composting toilets and was intrigued by the concept. I also really hated the amount of scarce boat space that was given over to holding tanks, pumps, valves and hoses . On the other hand I was still more than a bit uncertain about the whole concept of composting aboard a small boat.

My initial compromise in the spring of 08 was to take out the aft head and replace it with a composting fixture. Why a 40' boat has two heads is another thread and one that I won't go into here. Suffice it to say that that's what I had and what I had to deal with. It did afford me the opportunity to change one head and keep the other as a safety.

In the summer of 08 I took Genie on a cruise to Nova Scotia from my home port on the Hudson River. Everyone on the five man crew was quite leery of the composter and preferred to use the forward, old fashioned, head. While we were far offshore on the crossing from Provincetown to NS I decided to try to pump out the fwd holding tank. Something didn't feel right as I did so and I took a look under the bunks in the forepeak.

When I lifted the bunk boards I nearly had a coronary. The poly tank was bulging out in all directions and looked to be one more pump stroke from bursting. I had visions of driving the boat ashore and walking away from it never to return if something did burst. I had to open the deck outlet to relieve the pressure, resulting in a 2 foot gyser of raw sewage. Much scrubbing and cleaning later I swore to rid myself of all parts of that system, which had smelled bad anyway. (When I was dismantling the system later I found a sanitary product in one of the hoses that blocked the overboard discharge, the gift from a bubbleheaded guest of the PO)

During the return trip we were able to use pump outs and the crew remained shy of the composter in the aft head so I didn't really have a chance to evaluate it, though I used it religioulsy and found no problem with it. Last winter I removed the all the vestiges of the plumbing system and put in a composter in the fwd head as well.

This summer we cruised to Maine. I had anywhere from 2 to 4 crew aboard for a period extending to three weeks of sailing. People had to use the composters (or hang their posteriors over the pushpit) since we spent relatively little time at marinas. It was anchor or mooring, so they overcame their reluctance and used them. By the end of the cruise everyone was somewhat embarassed over their original reluctance and had gotten completely over their hang ups about it.

To fully discuss the pros and cons I have to give a brief description of the units and how they work. Essentially, composting toilets are made up of one "bucket" over another with a trap door between the two compartments. When the trap door is closed and liquid is deposited it runs into a removable 1 ½ gallon bottle in the front of the unit. There is a SS crank that can be used to agitate the contents of the lower container that is filled about halfway with peat moss and enzymes. A 1 1/2 " flexible hose with a fan at the deck end keeps a negative pressure in the lower tank to prevent odors from escaping.

If you are making a solid deposit you take a coffe filter (like those from a standard countertop coffe maker) and place it over the trap door. When finished you flip the handle that opens the trap door and your contribution drops to the lower compartment. The bowl is left clean because of the coffe filter. You take a couple of turns on the crank to mix your donation with the peat moss and that's it. If your donation was of the liquid variety I found it helpful to take a half a cupful of water to rinse the bowl and prevent it from developing odors.

Wow, I didn't mean to write the introduction to a book. At any rate here is what my conclusions are after one season of use:

Odors were not a problem with two exceptions. The urine bottle has to be emptied every couple of days or it does begin to get ripe. I have heard that a half a cup of sugar in the bottle keeps the odors down but I haven't tried it and I'm not enough of a chemist to understand if and why this would work. On the other hand it is not that difficult to clean out, either by taking the bottle to a shoreside head or by dumping it overboard (unless you are in a very closed harbor or a lake).

Part of the way into the trip one of the heads did begin to smell a bit, even after the bottle had been cleaned. A quick investigation revealed that the fan of the solar vent I had set up on deck to create the negative pressure to vent the unit had been jammed by a bit of caulking and was not functioning at all. I was pretty impressed that the unit had not smelled bad after a week of regular use even with no ventilation. I scraped off the caulk and had no problems from that point on.

We also discovered that the amount of toilet paper used by the number of people aboard tended to jam the lower compartment a bit. I was using regular TP so I don't know if using a rapidly degrading variety would work better, I'll experiment with that next year. I remembered that years ago, while in Greece, we were warned that the sanitary systems there did not swallow TP very well and near each toiled was a plastic bag into which you were expected to place the used paper. I bought some plastic zipper seal sandwich bags and instructed the crew to put the TP in the bags and thence into the garbage. Everyone caught on and dealt with it with no problem. The head was too small to install a bidet as an alternative.

The units themselves are pretty tall and it felt a bit funny at first to be so high, a bit like a kidergardner using grown up chairs. Most heads are placed on a shelf built into the liner so it is impossible to lower them. I am considering putting footholds so legs don't dangle in the air when sitting for shorter people. I got used to the altitude pretty fast as did the regular crew. It took some of explaining to guests.

And that's it for the downside. Not a long or impressive list. How about the upside?

Well, first of all, I am confident that I can deal with any head problems. These are extremely simple mechanisims. Nothing is hidden from view or inaccessible or impossible to reach. Everything is comprehensible and fixable. That is a huge plus. I also make sure I always carry a good supply of rubber gloves.

You don't need any assistance from the outside - last year in Nova Scotia where holding tanks were not required we had to search long and hard for a pumpout station. If your unit is overfull and you are offshore you just take the lower "bucket" and dump it overboard, rinse, refill with peat moss and start all over again. Total material from a crew still equals less than one poop from a medium sized whale, just make sure you are well offshore.

By removing all the tanks, pumps, valves and hoses I gained a tremendous amount of room. Both compartments under the two sinks were opened up for additional uses. The removal of the two holding tanks allowed me to install an additional 20 gal. diesel tank and to relocate my batteries.

The boat smells a hell of lot better. The hoses were getting ripe after 18 years of use and I didn't relish the job and/or the expense of replacing them. If you keep the composters clean they don't smell.

On the whole I'm glad I did the switch. There are problems but to me the problems are manageable because the system is simpler and much easier to maintain. If you sail for long periods with more than a couple of people one head may not be enough. My experience is that I can handle larger volumes for short periods or smaller volumes for longer. The manufacturer claims 80 uses during a season, you do the math. You leave the compost to work over the winter and in the spring the compost can be dug into the soil of your flower garden (not the vegetable garden!). I didn't want to discuss this with the Real Boss and so I fertilized some woods we own across the road. The deer didn't seem to mind and the material was indistinguishable from "black dirt". This year I might put it in the flower garden after all. This might be more difficult if you live in an apartment.

So this is what my experience has been after one season. I am not an expert by any stretch of the imagination but if asked if I would do it again on my next boat (if there is a next boat), I would say yes.
 
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#2 ·
Genieskip,

Thank you very much for taking the time to "compose" that outstanding write-up. That is hands down the most informative piece I've ever read on composting toilets. I'm sure anyone considering one of these units will find this very helpful.:)

Interesting pros and cons. I'm someone that has never had any real issues with conventional marine toilets (except holding tank capacity with our family 0f 5:eek: ), so I tend to view composting toilets as a solution in search of a problem. When it comes to bathroom functions, I prefer the "fire-and-forget" approach, whereas the composters seem to require a "man-in-the-loop". Reminds me too much of changing diapers. Been there, don't ever want to go back.;)

But I'm sure one burst holding tank could convert me...:D
 
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#219 ·
Genieskip,

Thank you very much for taking the time to "compose" that outstanding write-up. That is hands down the most informative piece I've ever read on composting toilets. I'm sure anyone considering one of these units will find this very helpful.:)

Interesting pros and cons. I'm someone that has never had any real issues with conventional marine toilets (except holding tank capacity with our family 0f 5:eek: ), so I tend to view composting toilets as a solution in search of a problem. When it comes to bathroom functions, I prefer the "fire-and-forget" approach, whereas the composters seem to require a "man-in-the-loop". Reminds me too much of changing diapers. Been there, don't ever want to go back.;)

But I'm sure one burst holding tank could convert me...:D
Well, John, that's the way way I felt about diapers till I became a granddad a couple of months ago and now all I can say is - been there, and glad to be back!
 
#3 ·
Genieskip,

I too spent my first season with a composting head (Nature's Head). We had no smell problems, and believe me we were looking for them. Every time we returned to the boat after a hot few days we'd open it up and take a sniff. I was expecting a problem with smell but had none. I vent ours up through a dorade vent, and you can get a stinky whiff if you are right downwind of the vent opening when the head is in use, but that goes away within minutes..after the stir I guess.

One thing I found, is that we filled it up before the season ended. I was hoping to go a season with it. I'm wondering if we added more composting medium (we used coconut husks) along the way it would have helped. I but in a fair amount at the beginning and that's it. I took the storage tank off the toilet last week, and cleaned it out. Much less gross than I would have imagined. It was almost like dumping a big bucket of potting soil. Not much smell at all.

Can I ask, how long you can go between dumping it? Do you add peat moss often as you use it??
 
#5 ·
I use it intensively for the few weeks I go seriously cruising with a crew (2 to 4 people) and very little the rest of the time, when I mostly daysail. In addition I have two units on the boat so I have not had to dump it more often than once a year in the spring - at least in my limited-so-far experience. I found that the coconut husk brick that came with the head didn't fill it enough and bought some peat moss, which I periodically added. That usually freshens the appearance of the mass, though it makes no difference to the odor problem, since I haven't experienced any odor problem. I do think it is important to add enzymes (bought at any hardware store, it's the stuff you put in your septic system).
 
#6 ·
I installed the AirHead, though from the pictures on the web the Nature's Head looks very similar. The hardest (and nastiest) part of the installation was the removal of the existing system. The installation of the head itself involves just a few screws. The only semi challenging part is the cutting of the hole in the deck for the exhaust fan. Rather than using the fan that comes with the unit I chose to buy a Nicro solar fan, preferring to avoid hooking up to my batteries the included fan that would be a constant (even though light) draw. Incidentally, when I bought my second head I spoke to the people at AirHead and they removed the fan from the package and lowered the price accordingly.

You have to make or somehow provide a hookup from the flex hose to the fan. I made one from a block of teak for the first one and bought a skimmer fitting from a pool supply place for the second. The bought fitting was much cheaper and easier to use than the fabricated teak. Over the next couple of days I'll try to get pictures of the fittings to post.
 
#7 ·
Would it be possible to run a poll asking how members feel about composting heads?
I get the impression that a whole lot of people are grossed out about the idea and it might be informative to get a real picture of people's attitudes.
I am of the opinion that composting heads could be very important in the future even in land based applications (think of how much fresh water could be saved) and if the subject received more attention perhaps some of the reluctance about them might fade. More importantly, the price might become more reasonable. I can't figure out why they are so much more expensive than conventional toilets. Maybe when the Chinese develop a knock-off the price will come down to earth.
So, how about it? Can we do a poll?
 
#8 ·
Sounds fine.

But before we set up the poll, let's make sure we're asking the right question(s). If you or anyone else wants to banter around on this thread a little bit, to come up with the proper poll questions, that would be great and then we could set-it up (it's high time I learned:eek: ).

P.S. I think you already know my answer.:D :D
 
#9 ·
Several of our Marine Parks have recently installed composting "outhouses"... different application without the space restrictions of a boat, but still miles ahead of the old 'smelly' pit toilets....
 
#11 ·
This just totally cracks me up. I don't understand where there even is a yuck factor with composters--at least relative to marine heads in general. What yucks me out is trying to pump solid waste down a long, relatively narrow pipe into an onboard, sloshing, cesspool, all the while praying that it never clogs going in or out! It must be the rough similarity to home plumbing that folks find comforting in standard flush heads.

I'll take an early shot at Knotheads questions:

1. Not at all opposed.
2. Yes--$300 or $400 would do it.
3. Absolutely

I looked closely at the Airhead two years ago and only had two problems: 1) pretty blasted expensive for what is essentially a plastic toilet with tank. Not a show stopper but youch 2) On our boat, the height would put the user's head smack into an overhang from the cockpit. That was killer.

I'm putting in a new holding tank for my sloshing cesspool this winter. :(

Tom
 
#12 ·
This just totally cracks me up. I don't understand where there even is a yuck factor with composters--at least relative to marine heads in general. What yucks me out is trying to pump solid waste down a long, relatively narrow pipe into an onboard, sloshing, cesspool, all the while praying that it never clogs going in or out!
Yeah, and then you get to carry it around in it's sloshing state until you get the opportunity to suck it out through another long hose. Yuck! I'd rather deal with some compost.
 
#14 ·
I'm pretty interested in this. What I don't understand is, are you guys saying that 4 people won't overwhelm this system over a weekend?

How quickly does the solid material break down? Would these units fit on a smaller, older boat that was equipped with a pump out head?

For instance, my Coronado 25 had a head that pumped directly to sea. No holding tank was installed. That's because in 1969, you could legally dump anything into the water.

Well, the head was removed, the thru-hulls plugged and 'glassed over and an RV cassette toilet is now sitting on the liner shelf.

Genie mentioned that the composting head is taller, so I'm wondering if it'll fit.
 
#15 ·
The specs for the Airhead brand can be found here: Looks like around 19" in height.

The reason 4 people wouldn't overwhelm it is that it's only storing the solids, and I suspect that even before the solids break down biologically, they shrink as they dry out.

On our boat I might have been able to fit one vertically if I was willing to cut into the fiberglass platform built for a normal head.
 
#16 ·
We're considering an Airhead for our boat, though we have yet to bite the bullet. Our current head/holding tank system needs some hoses replaced, there are long hose runs by design (which I don't like), we need to rebuild the toilet, and we might end up needing/wanting to replace the 26-year-old tank. Even without needing to replace the tank, there's enough there for us to look at whether we want to continue with this system.

Based on the type of sailing we do, an Airhead would not be out of the question. We're aware of the pluses and minuses, at least those discussed on this board, other boards, and on various web sites. For my wife and I, we like the environmentally friendly factor and the utter simplicity of the system.

At this point, I have no idea if we'll end up going with an Airhead. We may indeed just replace our hoses and move on. However, we're definitely considering a composting toilet.

Just some thoughts on the matter...
-J
 
#17 ·
Interesting

I like the idea of this head. I'd appreciate more input from experienced users.

I have two concerns with the system as I currently understand it.

#1 Cost, the unit is pricey.

#2 Lack of capacity for liquid waste.

Item #2 could be addressed if my existing holding tank could be used. Any information on using an existing holding tank for liquid waste only?

Paul
 
#18 ·
I like the idea of this head. I'd appreciate more input from experienced users.

I have two concerns with the system as I currently understand it.

#1 Cost, the unit is pricey.

#2 Lack of capacity for liquid waste.

Item #2 could be addressed if my existing holding tank could be used. Any information on using an existing holding tank for liquid waste only?

Paul
As far a item #1 is concerned, that's undeniable. Perhaps as usage increases price will come down but there is no denying that, at roughly a thousand buck, it isn't cheap.

As far as item 2 is concerned, unless you sail on an inland lake or always stay very close to shore and never stay at a marina, it really isn't too much of a problem. Perhaps my piloting is a mite off when I decide that I'm three miles offshore but, while I would never think of discharging solid waste, I have fewer scruples about losing a half gallon of salty sterile liquid overboard if I'm 2 1/2 miles off the coast. Whales pee out there too. Also the units come with a 1 1/2 gallon bottle that can usually hold a day's liquid for a normal crew. If you stay at a marina you can take the bottle to the head. All marinas rightly object to having partapotties and their chemical cargo dumped into their septic system but a gallon of yellow liquid has never bothered any marina I've ever stayed at. In case you need more capacity you can buy a second bottle. Three gallons should hold pretty large crew for a day of very inshore sailing.
 
#22 ·
Composting - required temperature??

I've read that below 70 degrees, the composting bacteria get "sluggish".

Does anyone know what the effects are if the temp drops below 60 overnight or for days on end when I'm not on the boat?

I'd really like to get a composter but am worried about the temp aspect during spring and fall here in the northeast.
 
#25 ·
I've read that below 70 degrees, the composting bacteria get "sluggish".

Does anyone know what the effects are if the temp drops below 60 overnight or for days on end when I'm not on the boat?

I'd really like to get a composter but am worried about the temp aspect during spring and fall here in the northeast.
Based on some experience with wilderness pit toilets, as long as there is regular use, the bacteria seem to kick off pretty well. If it sits for a while, things get stale. We also used to drop a packet of yeast and a teaspoon of sugar into the pits to get things going.

I'm pretty sold on the idea, as I need to tackle some sort of change to the current 'traditional' marine toilet I've got. I saw someplace that there is also a urinal type 'add on' available for not much... was pondering a set up that pulls that out for offshore use piped to the through-hull. Would cut back on the liquid volume as well as the requirement for sitting.
 
#23 ·
The reason 4 people wouldn't overwhelm it is that it's only storing the solids, and I suspect that even before the solids break down biologically, they shrink as they dry out.

[/QUOTE]

Okay, this post wins the award for euphemism content!

So, not only does sh*t happen, but it shrinks after it happens. So, if I don't give a crap about anything someone posts today, does that mean that I will care less tomorrow, or the offending post gets shorter?
 
#26 ·
I have a large Sun-Mar composting toilet in my home. I live in a rural area with very shallow soil and solid rock underneath that does not allow for a drain field as is necessary with a normal septic system. The unit works amazingly well. I use the same product in the composter as one would in a septic tank. It is a liquid that is named MICROZYME II and is made by Mid- American Research Chemical Corp. I use about 2 oz. of this stuff per month. Also I pour 1oz. of basic molasses in about once a week. For 2 people I remove and empty the compost probably 2 times a year. Sun-Mar also makes a marine toilet that is angled so that it rests against the hull. The only thing is that are pretty pricey.
 
#29 ·
This is an interesting thread.

I think that the issue of price is not being looked at in a fair light.

A composting toilet is a complete system.

A marine head is one element in the system.

To fairly compare you would have to account for the installation labor of each unit. The sum of all the parts; through-hull fittings, hose clamps, vents, hoses, etc.

You should also look at the time spent maintaining fixing each unit. I suspect that with a traditional head a lot of things are ignored until they finally break. At no time then is the entire system in perfect working order, each single element is at a different point in it's life span, spreading out the hassle and maintenance.

IMHO the composting head is on par with a traditional marine head system.

Also; the some of the sun-mar units can be factory set-up to drain excess liquids. Their website shows it draining to a gray water dry-well. A sailor could have it drain to a tank (in the space beneath the unit?)
 
#37 · (Edited)
This is an interesting thread.
I think that the issue of price is not being looked at in a fair light.
A composting toilet is a complete system.
A marine head is one element in the system.

To fairly compare you would have to account for the installation labor of each unit. The sum of all the parts; through-hull fittings, hose clamps, vents, hoses, etc.
I think you miss the point of the guffaws related to price.
Because it is a complete system, when you look at all the parts you actually get, and the complexity of those parts, it's sort of amazing you are paying 1K for some plastic, hoses, screws, etc.
The pricing of things should not be based on comparing a simple thing to a complex thing (that is the delta these guys are taking advantage of to charge a lot, but this is not how economics works for very long).

At the end of the day you have to assess what the thing itself is worth.
And for right now, these toilets are expensive for what they are - very intelligent, very simple systems.
I'm sure the price will come down as more people clue in to how effective they are.
 
#30 ·
Another question is resale value. I do not think there is any doubt that these lower the resale chances or value of the boat, by how much is not clear.
 
#31 ·
I'm not sure you are right about that at all. It would depend on who you sold the boat to. The heads are crazy expensive compared to a traditional one and as evidenced by this thread, there are some people forward thinking enough to consider the idea.
It certainly would not present much of a problem to replace a composting head with a normal one and then the thing could be sold for more than the replacement cost.

If we ever get a poll going, that could be one of the questions.
"Would having a composting head installed be a turnoff when considering a boat for purchase?"
 
#32 ·
I can easily see where they could be a turn off to potential buyers, having to haul the waste out versus pumping it out would tend to make people think twice.
(having grown up on a farm, while I don't -like- it, it needs to be done, so....)

I feel someone could make a suitable 'clone' at home with ease and avoid a lot of the fit issues, and depending on what materials they use, much of the expense could be sidestepped.
Though that itself could limit resale value, many people are 'afraid' of homebuilt systems simply because there is such a wide range of skill levels.

I like the idea because it is such a simple worry free system, and if it were designed with an easily removable 'bin' the range could easily be doubled (or more) simply by swapping bins. A 5 gallon bucket, brand new at home depot complete with lid is about $5, or available nearly anywhere for free, cheap enough to be disposable if you want.

Ken
 
#33 ·
We recently replaced our Thetford porta-potti with an Airhead composting toilet on our 25' Watkins. Never had a Marine toilet since we ordered the boat in 1987. Everything 'Genie' says is true. Having the Airhead lets us spend an indefinite amount of time in environmentally sensitive areas. Adding the coconut fiber or peat moss keeps the mix in the lower tank moist but not wet so non stinky aerobic bacteria can decompose the solids in stead of the stinky anaerobic bacteria that like wet environments like holding tanks. We happen to use 'Earth Enzymes' ordered on line. Just a little goes a long way, too much and there is an odor but is a 'sweet' sugary smell like rotting fruit. We keep a spray bottle of 20% white vinegar and water hooked onto the hold down of the toilet to spray the bowl half a dozen squirts after each use. Keeps the urine from smelling bad. We don't use the 'coffee filters' just open the dump lever before using. We buy the cheapest store brand of single ply toilet paper and use 'twice as much' but because it is already half the thickness it decomposes quickly like in days. Cost compared to the advantages already posted is insignificant factor. We have been composting for our gardens for over 30 years this is just the next logical step for everyone.
 
#34 ·
This is such a no-brainer to me. Why would we build up a "load" of septic waste in a tank in our boats if we dont have to. Clearly the aversion to compostin only comes from those who have never done it, so a lot of misperception going on there.
Having the extra space and never having to pump out toxic waste again both seem like all the reason we would need to make the leap.
Personally, if someone had already installed a composting system and saved me the trouble of doing it, i would favor buying that boat over one with a stink tank.
just my humble opinion.
 
#36 ·
In a discussion of heads late in the spring I mentioned that I had installed them in my boat and a few people asked me to write up my experience with them, so here goes.
genieskip

thanks for the report .. this is something that is definitely going to be added as a complete system rather soon ..

I will post details
 
#38 ·
I agree with emagin. It is a really nice plastic bucket with a toilet seat on it. If it fit my boat, I'd have gone for it at maybe $500. And even if you do compare it to a complete system, it would compare to something like a Jabsco self-pump toilet, given that it's not automatic and does involve user intervention. I can get a Jabsco head for ~$150, 12-feet of Odorsafe waste hose for ~$100, a Ronco 12-gallon tank for ~ $160 and have my system for under $500.

So they'd have me if it cost less (and I could fit it). But it could be that Airhead and the others assume theirs will always be a niche market and it's not worth trying to compete on price.
 
#39 ·
I'm by no means an expert here and we don't have a composting toilet, though we are considering one for the future. I agree the price is a bit high, and that has indeed kept us from biting the bullet. I do want to point out that I think the Airhead is made by a very small company. So the price might just be relative to what they can sell, and what they need to keep making them. It's not an automated assembly line running with robotics. Of course, I also agree that if more people bought them, eventually the price may go down. Doesn't help us right now though!
-J
 
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