Head Project: Desiccating Head


UPDATE 9/22/2014

We have had many requests for measurements of the head. Here is a post with the numbers: https://raindogps34.wordpress.com/2014/09/22/long-overdue-measurements-of-head/

UPDATE 9/1/2014

Link to main page about peat and other insights we have learned over the last year : https://raindogps34.wordpress.com/2014/08/28/the-staight-poop-on-our-dry-toilet/



From the beginning, in a galaxy far far away….

Well, where to begin…hmm, I guess it’s best just to lay out the facts.

Fact number 1, our current, though fairly new sanitation system stinks( literally).
Fact number 2, it is unlikely to get better unless we rearrange our holding tank set up, replacing all hoses and gadgets associated with, still leaving us with a fairly unsupportable long term system.

Current head



So, we are now desperate enough to try marine composting toilet systems. The marine composting head ( MDS Type III ) doesn’t really compost, but it does reduce and kill pathogens in a simple and stink free manner called Desiccating. Thereby, allowing us to dispose #2 in a safe manner( via flower garden compost pile or in a compostable trash bag in a dumpster). The number#1 gets pumped out at a pump out facility, poured in a land toilet, or poured over the side when we are not in a no discharge zone ( within 3 miles of land).

Here is an article about the virtues of a Marine composting toilet…http://ecovita.net/news/wp-content/uploads/2009/07/NaturesheadOnBoat2.pdf

I’ve decided to experiment with a camping toilet before spending a lot of money on something that may not work for us. I’ve uh er made a deposit, and noticed zero smell. I used peat moss and cedar shavings. For our permanent head, we will use coconut peat ( cocotek), a renewable resource.

We will be off boat for a week. Will let you know what greets us when we come back to the boat. I’m calling the head Obi Wan ( Kanobi) because it is our last hope….

Help Us, Obi Wan, You Are Our Last Hope..



Two Weeks Later:

Back on the boat. Head doesn’t stink! If there is a smell, it is an earthy smell with a whiff of cedar :-). So we are sold on the dry composting marine head. Brian is ripping out the wet head tomorrow and will begin the design and construction on a custom head. We are building our own because we cannot fit any of the manufactured composting heads in the tight little space. We ordered the urine separator ( keeps #1 and #2 separate) from Sanford Graves at C-Head. He has been really great with input too. I also ordered a nice strong solid wood toilet seat from amazon, the oval shape as I think it will work better with the urine separator.



Brian ripped out the head, I came in and scrubber the bejesus out of everything, this picture is before cleaning :-).

The hole from the old head hose will be a part of the venting system in the new head.

Two weeks later:

Brian and our friend Joe constructed the custom head. After showing me the basic template I asked Brian to revamp it to be much smaller, hopefully that is the right thing to do. Will update when I can.


In progress construction pic

Epoxying all the wood for the head. Wood ended up with three plus coats of epoxy and two plus coats of flat black enamel.


Urine Separator, bought from a company called CHeads



We installed the head in the middle of my epoxy/paint process to make sure we were on the right track. We had to trim the back ring of the urine separator off to accommodate a better “poo” hole. The black paint is an experiment to paint a non skid toilet seat. As you can see it looked pretty bad, so I painted the whole top flat black with the micro rubber beads for a non skid surface. Soft on the bottom and cleans easily.



I bought a fancy solid wood with brass fittings toilet seat. This ended up being too big. Brian found a nice compact wood toilet seat and lid at the local Ace Hardware that was perfect. After a few “trials, we decided to skip the seat and just fix the lid.

Below, the finished head.


I start each batch with a cup or two of cocotek peat and add about a 1/2-3/4 over the next two month batch cycle. I only need about a 1 gallon bag per batch. I also use a pet product called urine destroyer, it keeps the pee tank zero odor. We also bought a small dehumidifier since we do not vent to outside. So far this has worked just fine, no odors, no bugs.

No Pee While Standing Sign


The urine diverted is mounted beneath the toilet seat. The underside of the seat needs another coat of black paint, but I figure I will put a fresh coat of paint every year so will just let it go till then.



The inside workings, and yes that is a months worth of usage, NO ODOR!

The whole head comes together very tight, with very little room for shifting. The tank is held in place by the top of the head. Brian will install some positive latches so the head top and lid cannot come off in a knock down.


Total cost for head was $195.

Will update with any issues and such.


I get a lot of questions, which shows just how vague I was in my posts. So I will put this Q&A section here of all the questions asked of us in our dealings with this head.


 ? What is the difference between desiccating and traditional composting heads?

~~My husband explained it best just the other day. This is a cut and paste from that post.

“It (desiccating heads) does not really compost. Urine separating heads are actually desiccators, not compostors. It is actually almost the opposite. Composting is all about building up a large colony of aerobic bacteria (it is only the anaerobic that stinks as I understand it) to prevent odor. Desiccators are all about preventing any bacteria colony from forming by preventing any moisture. The bacteria needs moisture to survive. This is done by

1) Separating the urine from the feces

2) putting moisture absorbing materials in with the feces

3) mixing to make sure the moisture absorbing material can absorb all the moisture

4) ventilating to keep a good exchange of air in order to prevent moisture build up in the container.

All of this is supposed to keep anaerobic bacteria colonies from forming, thus preventing odor. You do not need heat, but ventilation helps. As far as I can tell, all urine separating toilets do #1 and #2 above. All commercial models also do #3. Not all, but some, do #4. We currently do #1, #2, and #3. #4 we will add if we need to, but not until then.”

? Do you vent your head?

~~ We do not vent right now. We plan to have a vent hose, around 2″, plumbed from the back of the desiccating head box to the Dorade box ( bathroom ceiling). So far we have zero smell and the compost is very dry, so the project to install venting is low in the list. *We do have a mini dehumidifier in the head constantly running while in port. 


? Do you have an agitator in the desiccating bin?

~~ No, so far we have not needed it. I bought a ss long handled spoon to mix and level the contents. It lookes like dirt, it smells like dirt. I have not needed to use it so far.

? What do you use for peat?

~~ We use Cocotek bricks. It is made from coconut. I think this peat is the best for bug prevention and is a renewable resource. I reconstitute a brick by putting about 3/4 cup of water in a ziplock baggy with one cocotek brick. It softens overnight and is ready to use.  I start each batch with about a cup or two of peat in the tank with a scoop of poo powder. With each deposit I add enough to cover, which seems to be about a cup or two. I also have cedar shavings that I purchased at a pet store($5), I add a cupful every couple days. The cedar shavings is apparently good for bug prevention.

? What do you do with your pee?

~~ the urine diverter collects the pee into a 1 gallon containers. We empty this container in the bath house toilets, or if in a discharge zone, it goes over the side. In the future, we may plumb to a larger bladder ( 20 gallon solar shower in the bilge) for longer storage situations ( like anchoring out while still within the 3 mile NDZ). This extra bladder should allow us to stay out 15 + days at a time, we can even shuttle the bladders to bath house or nearest public toilet…? We will see how that pans out. 

**Update combing soon, fitting small portable bladder with check valve so it cannot come back up the urine drain and quick overboard discharge option.

?What do you use for your poo bucket? 

~~ I use a 3.5 gallon bucket for poo. I line it with wag bags for two reasons, easy clean up and bugs are attracted to light colors, so the theory is the black bag helps keep bugs away. Bags are composting and are specifically designed to dispose human waste in them.




?Does your gallon jugs line up with the Urine separator?

~~ yes, three gallon jugs in a row automatically line the middle jug to the urine separator spout( pretty cool!). Spout is 10″ from head platform where the jugs sit.

?What do you use to dry the poo?

~~Peat will dry out the poo, I use cocopeat ( cocotek) it is a renewable resource and doesn’t have the bug problem others seem to have. They come in dry bricks that you reconstitute. So a year supply of peat fits in a small box( little bigger that a shoe box) I reconstitute 2 bricks at a time. One brick, each in a one gallon bag, add about 3/4 cup of water, seal and wait overnight. In morning break up peat, seal and wait another few hours. Be patient, the peat should be light brown, not moist, dry, very dry. They also make a product called poo powder, it absorbs water and is compost safe. Poo powder is good for times you have a crew with upset tummy, it will help the peat absorb the extra water. Also helps absorbs any pee that finds it’s way in.


Cocopeat Bricks ( Cocotek)

? What do you do with your desiccated poo batch?

 ~~ So far we bag it up every 1-2 months in a compostable bag and throw it away in the dumpster. The contents are dry and looks like peat, no odor. Many boat owners do not own land or have easy access to their land while traveling, for many, the trash can is the only safe option. I think the key to throwing away this type of waste is to ensure it is fully desiccated and the bag it is disposed of in is also compostable.


Disposed in a composting bad (wag bag), 1 months useage



13 thoughts on “Head Project: Desiccating Head

  1. Pingback: Homemade composting head - SailNet Community

  2. I like this, but is there any method of stirring it? I like the preloaded bag for emptying it, should make that task easier.

    • Sorry for the delay in answering. We do not stir. We decided to start simple and add a stirrer and/or forced air ventilation later if we see the need. So far, we do not see the need.

  3. i am really interested in making one of these for my cal27. do you have and drawings from your planning stage? what did you use for the urine tank? this would be a great winter project for my boat, while it is too cold to actually do much else. thanks.

  4. Love this blog!. I just pulled the graco head from my Del Rey 24. To use it this spring, I will have to install a holding tank, two way valve and vent. The present head used sea water, and direct discharge. the boat has been sitting for 10 years. I am going to install a head similar to yours and not go thru all the money and trouble of rebuilding and re–plumbing the old head. I would appreciate pic and measurements also. My head was sitting at the entrance to the v berth.

  5. Hi…can you PLEASE tell me the measurements of the urine diverter (front to back) that you bought from c-head? I just bought an antique toilet and want to add that particular diverter to the underside of the box. The plastic one sold by Separett seems too shallow. The entire toilet box measures 18″ x 18″ square, but the diverter you used appears rather long…so that gives me a bit of concern regarding fit. I will have to modify the top of the box anyway, as it has a very small hole…probably somewhere around 8″ diameter, and perfectly round…

    This will be for full time year round use…I am going to install a wall mount Panasonic exhaust fan just above the toilet to vent it to the outside air…that will also take care of any smell or humidity in the bathroom. It will exhaust 70 CFM and it boasts being nearly silent…uses only 24 volts.

    How does this diverter work out for keeping urine out of the bucket?? Is it difficult to clean? Does pee find any way to get underneath the diverter and drip down on the floor anywhere inside the box…or can pee splash upwards and escape if someone’s flow is very strong?

    As a side note, I am also thinking about using some Polymer gel beads (2mm size rather than crystals or powder) to add to the bottom of the solids bucket, in the event that urine is carelessly or purposely “spilled” by men who refuse to sit or are a bad aim…or if women have that occasional incident of pee running towards their backside. I read that Polymer gel beads absorbs 800 times their weight along with ALL odors as well…so two teaspoons per 5 gallon bucket spread on the bottom should suck out any moisture as it makes it’s way to the bottom if it gets pee’d in too much. I am going to buy a little and test it out…especially for smell. I am going to poop and pee in a bucket for a few days w/o adding anything else except the Polymer and see if it does what it claims to…this is the stuff “they” use in disposable diapers.

    Thanks ahead for answering my questions!

    • I haven’t forgotten about posting measurements! I’ve been sick, but as soon as we get back to the boat I will post measurements. One thing my hubby did is made sure the toilet was tall enough for the urine divider spout(drain spout) to fit under a one gallon jug. Not too tall, just high enough to capture the container with the drain spout. Make sense?
      Hopefully will be back on the boat soon.

  6. Pingback: A Copy Of The Original Desiccated Head Page | Dry Head Aboard Rain Dog

  7. Pingback: We’re getting the Flicka! – NOTES FROM A SMALL BOAT

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