Our Composting Toilet

By Carolyn Shearlock © 2016 • all rights reserved

The learning curve for our Nature's Head composting toilet has been steeper than expected, but we love the unit. Here's what we wish someone had told us.

Eight months ago, we ripped out our standard marine head and replace it with a Nature’s Head composting toilet. So, how are we liking it and what have we learned?

Bottom line: we’re really happy that we made the switch, but there has been much more of a learning curve than we expected . . . and in talking to numerous other people with composting heads, that seems to be the case for well over half of new owners.

We like it for all the reasons we thought we would – no holding tank (ours was tiny), no pumpouts, virtually no smell, and the ability to be in remote places for long periods.

But it has taken us eight months to get to this point . . . and at times we really wondered if we had done the right thing. Did everyone just say they liked their composting head to justify having bought one?

Here is what we wish someone had told us when we first began using the Nature’s Head. Hopefully, it will help others who have installed one or are thinking of doing so.

COMPOSTING MEDIUM

First off, it’s important to know that we’re using coconut coir as the “composting medium” as opposed to peat moss.

  • Coconut is easily renewable (it’s coconut husks) while it takes millions of years for peat to form.
  • Coconut coir is much more compressed than peat moss, so it takes a lot less space to store.
  • Peat moss can come with bugs in it . . . coconut doesn’t.

Coconut coir has to have water added to it and then be crumbled up before use. It expands tremendously as water is added. So here’s the dilemma: add too much water and you’ll have a foul seepage around the crank handle; don’t add enough and it will absorb water from the waste deposits and expand and overfill the compartment so that the handle won’t turn.

We had both problems as we tried to figure out the system. At first we added the amount of water stated on the coconut package for reconstituting it to use in a garden as a soil additive . . . which was way too much. We were then told to use just 5 cups of water per brick . . . but given no size or weight info on the “brick.” That was way too little. Finally, we were able to find out exactly how much water someone was using for a specific weight brick and were able to extrapolate from there to our bricks:

  • We now use 18 cups of water for one 2.75-pound brick. [UPDATE: based on some reader comments below, we now use just 1 cup of water per 2.75 pound brick, and initially fill the composting bin about 2″ short of the agitator.]
  • We have learned that it will still absorb some moisture from the waste, and instead of filling the composting bin level with the agitator (as directed by Nature’s Head when using peat moss), we fill it to about 1” below the agitator. [Se update above for new level.]
  • Sometimes, after about a week, we have to open the bin and use a stick to dig the compost material out of the corners and get it into the mix.

NOTE: We do not put toilet paper into the compost bin. It takes up space and can tangle with the agitator. We never put paper in our regular marine head, so it wasn’t a big change for us.

HOW OFTEN TO CHANGE

We have learned to change the composting medium at about 3 weeks, or 21 days. There are two of us aboard full-time. We’ve tried letting it go longer but frankly, it was pretty nasty to change. By changing it sooner, it’s a lot nicer job. Pre-purchase, things we read led us to believe that we’d get 30 days between changes. My guess is that those people perhaps work ashore. Other brands, number of people and so on will require a different schedule . . . but the bottom line is that if it’s nasty job, you’ve let it go too long. Try a shorter interval.

Now that we’ve got the procedure down and aren’t having to clean up a mess because of too-watery coconut, it takes us about 30 minutes to change it.

COMPOSTING

If you are using the unit full time, it will not be anywhere close to composted when you change it. This is a misnomer. Unless it goes into a compost bin for considerably longer, it is not compost. Even if it is left long enough to compost, it should never be used on food crops.

BUGS

By not using peat, we’ve cut down on the bugs considerably. But let’s face it, we live in the tropics. There are bugs. And they love poop. Anything you read will tell you to use various amounts of diatomaceous earth to get rid of them (see what we bought on Amazon). It did not solve the problem for us and apparently for some others we know in the tropics.

Oh, we still use some diatomaceous earth as we don’t know if the problem would be worse without it, but a friend told us of another product that has helped far more: Rid-X Septic Tank Treatment Packs (Amazon). We use 1/2 of a pack at a time and mix it into the fresh compost when we change it. It’s a dry powder that helps the waste break down faster, the theory being that bugs aren’t interested in the waste once it starts to break down.

VENTILATION

We hooked the vent hose up to our old pump out port and put a mushroom vent on it. Nature’s Head comes with a fan that is wired into our 12-volt system and draws next to nothing. Three things that we’ve learned:

  • It’s easy when you lift the seat to remove the urine container to slightly dislodge the electric plug for the fan. Any time you lift the seat, check that the plug is secure and that you can hear the fan running.
  • SHUT THE MUSHROOM VENT when underway (also unplug the fan). If you take a wave over it, the water could swamp the compost . . . and friends who got water down the hose had it cause their vent fan to stop working. (Carrying a spare fan wouldn’t be a bad idea . . . we’ll get a spare when we’re back in the US.)
  • Periodically clean out the vent intake and fan on the seat and on the deck fitting if it’s screened. You want all the air flow you can get.

SMELL

There is very little odor associated with the composting head, but there can be a little when the compost bin has been open while emptying the urine or when changing the compost (or if you have a problem with urine getting in the compost or too-wet compost). There can also be a little smell when we’re underway and the vent is turned off.

Instead of air fresheners, we found a product we like much better:  Med-Aire Biological Odor Eliminator (Amazon) – it was designed for hospitals, nursing homes and the like to actually remove odors instead of covering them up. I also use a quick squirt of it in the trash can where the used paper goes. An 8-ounce spray bottle lasts us over a year. (It will also remove odor due to seasickness and almost anything else that’s “biological” including dog and cat odors.)

CONCLUSION

Almost everyone, it seems, has problems getting the coconut/water ratio right to begin with, and most internet sources just give descriptive terms such as “moist” or “not wet” or “quite dry.” Those are all very subjective and we found them not helpful. Even the YouTube videos we watched of someone preparing coconut coir didn’t give a “recipe.”

Once someone told us their mix ratio, 90% of our problems were solved. It’s also important to use less coconut in the initial fill than peat moss, as coconut swells as it absorbs water and peat doesn’t.

Someone asked me about the “yuck” factor of dealing with emptying the urine bottle and changing compost. We find both to be far less objectionable than changing joker valves, pumps and hoses on a traditional marine head . . . all of which occurred with annoying frequency. Those parts also cost considerably more than the coconut we use. Finally, dumping urine or changing coconut are relatively quick jobs compared to many of those on a traditional head and, if something else is going on, changing the compost can be put off a day or two. If a traditonal head has a blocked hose, sorry – it has to be fixed right then.

The benefits of the composting head are tremendous and will pay off for years. We don’t regret switching at all and recommend the Nature’s Head brand (admittedly, we have no experience with other brands). It is so much better than dealing with a traditional marine head . . . and we now have two fewer thru hulls!

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Comments

  1. Tom Geren says:

    Good to read the straight poop Carolyn. I’ve read too many forum posts about how (ridiculously) long the high dollar heads can go between medium changes. I have the smaller C-Head and use peat but am also very happy to have made the switch.

  2. Hugh Burton says:

    We’ve used a NH for two seasons on our Macgregor 26M . Not as extensively as you as we are seasonal sailors. We will Be living aboard this summer in NW Ontario ( much more temperate). We are using peat moss so found the info on coir of interest. So far no no bugs!

    • Coir is much more environmentally friendly, hope that my info will help others make the transition away from peat if they don’t have such a learning curve!

      • Hugh Burton says:

        For Canadians, we found coir in stock at the Home Hardware. HH is really good at ordering in product so access is good.Will be switching to it when we do the next changeover.

  3. This article is right on time. Thank you for sharing your experiences with the Nature’s Head. My husband, Michael Ganey, installed ours of Memorial Day weekend but we haven’t used it yet. We also chose the coconut coir but the brick we got was very large and we wouldn’t know how much water to add. Also good info to know regarding the fan. You’ve saved us some steps in the ” getting to know you” phase of our composting head. Thank you, fairy god boaters!

  4. Happy to hear all is going well with the NH. Enjoy your time in the Bahamas.

  5. If you haven’t already taken the old thru hulls out, you might consider using one of them for a saltwater washdown pump. We mounted it in the sail locker. So handy, particularly when anchoring in muddy areas.

  6. Are you still required to be 3 miles offshore to dump this without risking a fine?

    • If you want to just dump it into the ocean, yes . . . or 12 miles in the Florida Keys and other special protected areas. Most of us put the bag of used material in the trash dumpster — it’s perfectly legal, just as putting disposable diapers in the trash is legal.

  7. Hi
    We bought an Airhead from the US for our boat built in the UK which is now on the Spanish/Portuguse border. We’ve been using it for 2 years now, 2 of us on board, and very happy. When we purchased it we got a bag of coco husks if I remember rightly. This never worked for us and we couldn’t buy them locally either. We use sawdust as prepared for pets such as hamsters/gerbils. We also used a composting powder the first couple of times too. After using the loo, we add a handful of sawdust and agitate it frequently. Also, when we empty we leave a layer in the bottom as the composting process is already working on this. We have found bags of sawdust readily available in supermarkets pet aisles in UK and so far in Spain and Portugal. A bag lasts us months. Also, as it’s so light we can stock up if we thought supply would be an issue. I’d recommend a composting toilet.

  8. Also, I found that women have to do a bit of adjusting where they sit, to make sure liquids stay out of solids. Totally worth it, we have a NH.

  9. Charles says:

    The friendly manufacturers of the C-Head and Boondock Jonny have a great video on various composting mediums at YouTube.

    https://youtu.be/SUJRJxf_uMk

  10. Some of the challenges you wouldn’t have with a Air Head. 🙂
    I love the freedom that we got from our Air Head. We live aboard and in the winter there is no pumps working so it is just great to be able to use our own toilet anyway. I agree with you in the receipt of the cocos coir. My bricks change in size too so I always start with less water and add a bit more if necessary. ☺️
    Thanks for sharing!

  11. Scott Smith says:

    Carolyn…on the amount of water to reconstitute the coir, just a suggestion to try. We have a C-head, but also use coir, so I would think things would be similar. FWIW, I don’t use anywhere near the amount of water that you do. I purchased my coir in a 5kg brick and cut that into quarters (so about a 2.5 lb chunk each). I cut each chunk in half, and put each half-chunk (about a pound or so) in a 1 gallon zip lock bag. I add about 6 or 7 tbs (yes, tablespoons) of water to each bag and put it out in the sun. Be patient…up north here it might take a day or so. Next day, I take a table knife and split up the coir in the bags and break things apart using my fingers. At this point I might add a little more water (but I’m talking 3 or 4 tablespoons). Put the bags back out in the sun again, and attack it again later. Bottom line is to use as little water as possible to get the job done, so the coir can do it’s job and absorb the moisture in the waste, not start out saturated to begin with. These heads are really desiccators, not really composters, per se. My 2 cents, but this method works for us.

    • One of our “experiments” was to try using just a tiny bit of water. Our problem was that it expanded so much with the moisture from the poo that it overfilled the container. I think that if I tried using the very dry coir, we’d fill it maybe only 1/3 as full as we do with the moister mixture so that there is room for it to expand.

  12. We’re at our year anniversary living aboard full time and cruising (currently in Caribbean) with the Air Head using coconut coir. We’ve had about the same learning curve you did. We make an effort to break down the unit every couple months or so, and rinse everything out with fresh water (hose, base, tank) to reset. I realize that this removes the enzymes, but we add enzyme powder and it’s been a lifesaver with bug prevention.

  13. We have an Airhead and love it. Two more warnings, though. The urine vs poo separating mechanism is designed to work when the toilet bowl is in a parallel plane with the earth. If you’re on a long passage and heeled over for days or weeks, this can cause toilets mounted athwartships to have issues getting the urine to go into the pee bucket because the toilet is at an angle.

    For example, our toilet is mounted athwartships against the port hull. When we’re heeled over to starboard, it works fine and the pee runs downhill and goes into the pee bucket. When we’re heeled over to port, the pee has to run uphill to get to the pee bucket. Some always makes it there, but occasionally we get a puddle hovering at the back of the bowl.

    If you ease the sheets a bit so that you don’t heel so much, the pee will find its appropriate spot. (It’s also easier to sit on the loo.)

    Second, we have a stash of coir bricks we’ve vacuum packed with our food-saver machine so that, if we had water reach the storage area, the bricks wouldn’t “inflate” and get ruined. However, it does kinda look like we’re smuggling hash! We’ve never had customs search our boat, but I have the toilet information copied and stored with the bricks, and bricks clearly labeled in two common languages just in case.

    Like Carolyn, we use the septic tank germs from the hardware store plumbing section to help turn poo into not-quite-poo more rapidly. Just think of it as magic pixy dust and sprinkle a little in every now and then.

    Even though coconut coir isn’t supposed to have bugs, one of our bricks apparently had mold mites in it. (We just emptied the poo bucket, washed it well, let it dry, and dusted it w diatomaceous earth, leaving it sit unused for a few hours after. That took care of them.) Now, I reconstitute the bricks in a big plastic bucket and nuke the material in the microwave for a minute before putting it into the toilet. I figure that ought to kill any bugs or bug eggs. Then, I sprinkle the septic tank germ “pixy dust” into the bin to replace any “friendly” germs I inadvertently killed in the microwave. I don’t HAVE to do this extra step. I just hope it will prevent giving our toilet a bug infection from any bugs that stowed away within the bricks.

  14. We have had a Natures Head now for over 2 years. While in the yard, off the water, we had no problems but when we started cruising the Pacific fulltime the fans started going bad. It’s not the fan that goes bad but the wires corrode and go bad. I have to say Natures Head is wonderful with their warranty. When I e-mail them they send 2 fans no questions asked, no charge. I am now on fan 5. This time I will be taking some rubber electrical liquid and coating the wires. I’m hoping this will cure or retard the corrosion.

  15. Laura dwan says:

    We have had ours for 4 years, sailing the Pacific. About every 6 months, when we are in a quiet anchorage, I hang the whole unit overboard and let it soak for about an hour. Gets rid of bugs and little bits of peat the get stuck in the crevices

  16. Beacon Hill Ben says:

    We will be installing a Thunder box in our catamaran, really just a big plastic bucket toilet, complete with a toilet seat and lid. You use bio-degradable liner bags in it (made of plant starch), after doing your business (1 & 2, plus toilet paper, paper hand towel) you tie a knot in the bag and you discreetly throw it overboard, it bio-degrades within 7 days… You then put a new liner bag in the bucket and hey Presto: a clean toilet! The bucket costs about $30, the bags are about 10c each. No fans, no pumps, no sea water, no nothing. And yes, my GF has agreed to this, she likes this a whole lot better than carrying a ‘black water’ tank around with 60 liters of our poo!
    Oh, in a marina/anchorage you can’t throw the bags overboard of course, we store them in a second bucket w/lid in our garbage hold. You dump them either in the marina rubbish bins or overboard once out at sea. I’d say that the toilet bucket is the most cost effective, hygienic, easy-to-use, fool-proof system of all on-board toilets. And it only weighs 4Kg/8Lbs!

    • I’ll be interested to see how it works in practice. In Florida, for example, you have to be 12 miles offshore to dump. I think it will also be “interesting” if you have guests . . .

      • Beacon Hill Ben says:

        All my friends are quite capable of tying a knot in a bag. If you can’t dump overboard, you use the bins in the marina. Our storage bucket (out in the garbage hold, not in the cabin!) can store 3 weeks worth of ‘baggies’ but I hope not to keep it that long.

        • Tom Geren says:

          This is hardly new technology. Folks have been dumping in plastic 5 gal containers lined with plastic since plastic material was invented in 1967 as characterized in the famous Mike Nichols’ movie, “The Graduate.”

  17. You convinced me. Will be switching out the head for a composting one this summer

  18. Good summary. After having tried coir in our C-Head, adding only enough hot water to crumble it, with satisfactory, drying, no-bug results, we switched to dry cypress sawdust leftover from our interior paneling project. So far, so good, pleasant, and free. Given our short trips so far, we are saving those compressed coir bricks for later, when storage space is at more of a premium. We haven’t found it necessary to fill the solid waste bucket with fiber or sawdust. About half full, adding a bit more as needed, seems to work for our episodic three-day voyages. Nor have we found it yet necessary to scrub after emptying it, which may change with more rigorous usage. (We hope to give it, us, and the homemade boat a proper workout later this year!)
    The C-head’s removable crank inserted on top through the seat and lid, to stir after use was a great engineering idea, as the side cranks take up space and seem to have that leakage problem.
    Yes also, to the learning process for female positioning. Being mindful at first seemed to work for me.
    Whatever brand of “composting” head a prospective swapper can find room for and can afford, the olfactory contrast between new composter and old flush head, hoses,and holding tank will provide excellent relief!

  19. Jenn and Terry McAdams says:

    We’re on our third season here in Nova Scotia with an Airhead on our Cape Dory 31. We take a long (3 months or so) live aboard cruise each summer. Our early experiences with the composter were not positive and we think it definitely did not perform as advertised. We had some leakage and learned quickly that the solids tank will fill long (very long) before any composting takes place.

    We left some solid waste in our tank over the winter and it still is not completely composted. However, we were not here to crank it and add moisture every so often but who would do that over winter storage?

    Also, the liquids tank is very small and can be a spill hazard when you empty it (see below).

    Still, for us, it’s an improvement over the old Grocco head. One change we made was to plumb the the liquids tank to our (rather large – 28 gallons) holding tank. This really extended the capacity of the holding tank. We learned after the first season of this arrangement that mineral deposits had nearly clogged the drain hose. Last year we added a larger diameter hose (3/4″) and we pour a cup or two of white vinegar in the liquids tank every week to further prevent mineralization.

    Note that, if you’re installing a fitting for a drain hose on your liquids tank, you need to use a special glue, the 2-part kind they make for Starboard plastic. Tightening the fitting nut inside the tank is impossible (for us, anyway) so we just used a threaded fitting and lots of glue.

    We echo all the other comments above. We do use peat moss and just mist the tank with a little spray bottle once a day or so to keep dust from clogging the screen on the vent hose, which is a bit of a pain to remove, disassemble and clean.

    Airheads aren’t cheap – a grand or so plus a few hundred for parts to make changes. Also, this head is high and a shorter person can’t have their feet on deck while using it. This problem was even worse on our boat, which has an elevated little deck in the head for head mounting. So, we got some (pricey) 1/2 starboard and made a little deck under the head with just enough width to set you heels on. It works, but was a day to install.

    That’s all for now. If any of you are in Nova Scotia and want to see our head installation, let us know. Note, we’ll be heading south on July 2 for NYC, then up the Hudson to Champlain.

    Happy sailing to all!

    Jenn and Terry

    • I wonder if part of your situation – not composting – may be temperature? We’re in Maine, and notice a very significant change in composting speed as the temp is lower at each end of the local sailing season. Still, with two of us aboard for 3 weeks in late August we didn’t’t come close to overloading our Airhead.
      Appreciate your input! Wondering if the septic tank enzymes would help you? Perhaps you’ve tried that…

  20. We are liking a mix of coco coir and “pine cobble” cat litter in our C-Head. (These days, that is to say. Toilet media choice is an ever-evolving situation.) Anyway, the “pine cobble” is the same as the pine pellet cat litter, it’s just not pelletized. So we and our cat are using the same litter, ha ha.

    Def like the coir better. Haven’t had bugs again, and it’s just easier to work with

    Amelia, if you are the same, thanks for your advice (on feminine positioning lol) when first got the CH

  21. A couple more thoughts:
    I wonder if a different solid-waste-drying medium would present less of a dust problem. Peat IS dusty, in addition to its other drawbacks. Adding moisture to it would slow the desiccation (not composting, which is a misnomer) process, wouldn’t it?
    Our C-Head uses ordinary one-gallon screw-capped plastic jugs for urine collection. (The company does offer, I believe, a way to collect larger quantities in a container below deck, but why would you want to save it? That is what gets stinky, as bacteria grow in previously sterile urine. A reasonable case for frequent emptying, maybe. ) Advantages of the milk jug approach include free containers, easy to obtain, fairly light and easy transport for proper and frequent, discrete emptying, no problem discarding the repurposed container when it gets discolored and scaly. Only disadvantage I’ve found is how quickly two thirsty people can fill a gallon jug. We carry several spares, empty and rinse whenever we stop for fuel or docking, and replace the jug with an empty one every night.
    So far, no disasters, overflows, leaks, or spills, and no odor at all.

  22. We bought a C-head one week ago. Definitely like the low odor aspect to it and still learning as we go! As a woman I have had to buy a funnel to help me separate the solids from liquids but it beats having to deal with a holding tank and stinky hoses! We are going to add sugar to the urine jug as it is supposed to help with urine odor. Will keep everyone posted on our progress. Or I should say my progress ; )

    • Jenn and Terry M. says:

      We tried adding sugar to our liquids tank a few years ago. It didn’t seem to help much and, we believe, contributed to mineralization of the hose we installed from our liquids tank to our holding tank. Now we just pour in a cup or two of white vinegar every week or so. Seems to work.

      Good luck

    • Vinegar did far more than sugar for odor with us, too. Don’t use nearly as much and Jenn and Terry — maybe a 1/4 cup?

  23. Sage Seeley says:

    Living in the Keys, where it is hot & humid. Bugs can be a problem. I have had my Air Head for 4 years now. Last year I experienced bugs in my toilet for first time. It was a real problem, until I spoke with Air Head about it. First I cleaned the toilet out with hot water, followed with a gallon of vinegar. You need to make sure you get all the eggs, look like rice, out of the toilet. Repeat his process 10 days later to make sure the eggs were killed. I was using diatameacus earth mixed into compost, I was told to not mix but sprinkle on top of compost. I do this each time after cranking & have had no further problems. Leaving the brick in hot sun to help break it down after adding water also helps further sterilize the brick & eliminate problems.

  24. We have a Nature’s Head for an outdoor pool bathroom at our swim school. We’ve had some interesting learning curves as well! For one, the wet users allow the coir to get too wet with the poo hatch is open causing bad smells, gnats, seepage from the side, and it getting full too fast. Also the small amount of chlorine from the saltwater pool probably doesn’t help the composting process either! Since installing it a year ago we’ve found that shavings of dry coco coir barely covering the bottom has worked best for us. Of course that means you can’t use the crank to stir it, but we’ve had this amount of coir in there for a month with a potential of 50-60 users a week and still haven’t added any extra. Today when I checked it I found large mushrooms growing for the first time and no bad smell. Since it wasn’t composting or even breaking down well (we figure due to the chlorine messing up the environment) we just purchased a second tank to swap in and now keep the full one in a sunny spot to finish composting. We’ll see if this works. Such high usage has sure been a challenge!

  25. Coir can sometimes be difficult to find in the UK but IKEA has 5 litre bags in a compressed form that is ideal for storage when cruising…Just add water…And if you add just enough to create the expansion and leave it a little dry, the moisture in human solids helps to swell the material and is so partially dried in the process of mixing.

  26. doug siddens says:

    Peat moss is so slow growing that it can be considered non-renewable. Coir is quite renewable.

  27. I love the idea but wonder how this works for long offshore passages. If you are caught in a blow for a few days, you have to completely shut down the ventilation system and secure the vent. I’m thinking of a 13 day passage from Norfolk to the British Virgins in November, where we had to have the boat closed up for 7 days in a row. I’d greatly appreciate thoughts. Thanks

    • There will be some smell, but I don’t think it will be horrible. The longest we’ve had ours closed up is about 3 days, and it wasn’t even terribly noticeable. It will definitely help if you start with fresh compost. You can also mix about a cup of baking soda in to help absorb any odors (we did not do this as ours happened due to a fan failure, not a planned passage — but friends have told us this trick).

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