Installing a Composting Toilet | |||||||||||||||||||||||||||||||||||||||||||||||||||
In 2008 the toilet in Sarah's head was showing a lot of age and needed either to be replaced or a major overhaul. Also the LectraSan sewage treatment system was about to give up the ghost and it was not even legal in many areas of the US. So a holding tank was probably going to be required, something that would be difficult to fit on Sarah and a lot more plumbing. After having to clear a sewage hose on the way from Bermuda back to the Chesapeake Bay in 2007 I started looking for alternative to the standard seawater flushed marine toilet. | |||||||||||||||||||||||||||||||||||||||||||||||||||
The Airhead Composting Toilet |
The only real alternative is a composting head - one that does not discharge sewage, but rather allows it to compost onboard turning it into fertilizer. I heard of this type of head for years, but the concept seemed a bit extreme. However as the concept of a discharging head became more and more undesirable, the alternative began to appear much more acceptable. Practical Sailor had done a review of several composting heads back in 2002, and they concluded that it was a workable solution for a marine toilet. I also heard from several live-aboards who installed composting heads on their boats and were very satisfied with the arrangement. | ||||||||||||||||||||||||||||||||||||||||||||||||||
At the time I was only aware for one brand, the Airhead (shown in these pictures), from the Practical Sailor article, the live-aboards, and boat shows. So in 2008 I purchased the Airhead and began planning the installation. Subsequently I learned of another brand, Nature's Head, which also would be a good solution for Sarah's Head. |
The Airhead Composting Toilet |
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The Airhead Composting Toilet |
The base of the toilet is the composting chamber. The toilet bowl detaches from the base and the base can be removed from head to dispose of the compost periodically. Live-aboard couples claim they can go up to six weeks without having empty the chamber. The other chamber protruding from the base is the urine bottle. The secret to composting is to control the moisture in the composting chamber. If urine were added to the chamber the compost process would take much longer (until the urine evaporates) and probably would produce unpleasant odors in the head. | ||||||||||||||||||||||||||||||||||||||||||||||||||
This is the business end of the Airhead. In the interest of good taste I've taken these pictures before the Airhead was installed and before it was ever used in anger. |
The Airhead Bowl, Trap Door Closed |
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Airhead Bowl, Trap Door Open |
In
this picture the trap door to the compost chamber is open.
That is all there is to flushing this toilet - allowing the waste to
drop into the chamber. The manufacturer recommends using Mr.
Coffee-style coffee filters to catch the waste before the trap door
is opened, but several users claim they no longer use the filters,
but just drop their business directly into the chamber. Maybe this is more information than you really want. The two holes in the toilet bowl, forward of the trap door are used to collect urine. Yes, this is a gender-equalizing toilet. No one gets to pee standing up in Sarah's head after this toilet is installed. |
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The
Airhead uses a standard compact marine toilet seat - the same as on
the Raritan PH-II head that came with Sarah. One difference is
that the Airhead provides gasket seals on the bottom of the seat and
the lid to contain any odor. One of the advantages of the Nature's Head composting toilet is that it has a standard household toilet seat molded into the unit. Since my butt is definitely not a compact size the full-sized seat might be a significant advantage. Still I've managed to get my business done on a compact seat for the nearly 5 years of living onboard, so I guess I can continue to get my business done on the Airhead. |
Gasket Seals Under the Toilet Seat and Lid |
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The major installation task (other than removing all the old plumbing) is the installation of the vent which brings air into the composting chamber. I wanted the vent hose to be out of the way on Sarah and not take up a lot of valuable space in the small head. The ideal spot is in the little alcove just outboard of the companionway stairs that are on the opposite side of the forward bulkhead. | |||||||||||||||||||||||||||||||||||||||||||||||||||
Liner Removed from the Head |
So first I removed the headliner. This involved removing a lot of molding and trim pieces. Even then the headliner resisted coming out. Clearly the headliner had never been removed from the head since Sarah was built. | ||||||||||||||||||||||||||||||||||||||||||||||||||
The headliner did finally come free and I could see the underside of the trunk cabin where I intended to place the vent. There is a 1/2"x4" piece of wood glassed into the corner of the trunk cabin to provide stiffening. The 3-1/2" hole for the vent would have to partially cut into this stiffener. That meant I would need to fit some cleat stock inboard of this to provide a flat surface to attach the vent fan. |
Location for the Vent |
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Cutout From the Coach Roof |
The first task was to cut the hole in the trunk cabin with a 3-1/2" hole saw. The edge of the cut-out is shown in the picture on the left. The trunk cabin is about 1-1/2" thick with a 3/8" outer skin of fiberglass and a 1/4" inner skin with 1" of balsa completing the sandwich. | ||||||||||||||||||||||||||||||||||||||||||||||||||
On the right is the hole in the deck with the cleat stock installed. Notice the air gap between the cleat stock and the coach roof stiffener. This was an installation error that I had to correct a few years later. |
Hole for Vent and Cleat Stock Air Gap |
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Vent for Airhead in Place |
On the left and below is the deck vent fitted next to the companionway hatch. | ||||||||||||||||||||||||||||||||||||||||||||||||||
This is a passive 3" Nicro vent. |
Nicro Vent |
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The Airhead Fan Housing |
In
this picture the headliner has been re-installed and the vent fan
housing installed under the new opening in the coach roof. I cut this corner of the headliner off from the main piece. This made it easier to cut the hole in the headliner for the vent opening, but it will also allow me to remove the main part of the headliner in the future without disturbing this vent for the toilet. The fan housing is secured by screws that go through the headliner, through the cleat stock, into the coach roof. This housing must support the weight of about 6' of 1-1/2" vent hose, so I want it to be very secure. |
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Now all I have to do is hook the fan up to a 12 VDC supply and I can remove the old PHII toilet and install the Airhead. | |||||||||||||||||||||||||||||||||||||||||||||||||||
This
is a picture of the vent opening in the coach roof with the Nicro
vent removed. The vent fan is visible. Yes, I know I really chewed up the coach roof gel coat with the hole saw. I drill one of these holes about every 5 years and I always forget that when using a large hole saw in hard material you have to run it in reverse, at least until you get through the outer fiberglass shell. I am starting to believe I have forgotten more things than I ever knew. Getting old is a bitch. |
The Vent Fan |
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The picture above also exposes a major mistake I made in the vent installation. There are air gaps between the glassed-in plywood trunk cabin stiffener and the cleat stock I added. This allows some of the air coming from the compost bin to escape into the area between the headliner and the trunk cabin roof. When Steve Angst and I were taking Sarah south in the fall of 2008 we noticed there was some odor in the main cabin, but none in the head. I couldn't figure out how that could be as the hatches were closed and the wind was blowing over the bow and should have pushed any odors aft, not down in the cabin. When I was updating this page I noticed the gap in this picture and suddenly realized how those odors got into the cabin. That was also a time when I was still experimenting with how much COIR to add to the bin. With sufficient COIR there are no odors, and this gap is not a major problem, but it needs to be fixed. I will probably use some rope caulk to fill the gaps. | |||||||||||||||||||||||||||||||||||||||||||||||||||
Added Butternut Trim to Cover Wallpaper Gap |
While I was messing with the headliner and trim pieces I decided to finish covering the places where the wall paper had been removed during the bulkhead replacement. I found some of the Butternut stock I had used for trim around the bulkhead. I used that wood to cover the gaps in the wallpaper. I still have to shape the pieces a bit and then varnish them to match the other Butternut trim in the head. They will not match the original teak trim pieces, but I will not add anymore teak to Sarah' interior or exterior. | ||||||||||||||||||||||||||||||||||||||||||||||||||
Finally on May 30 I removed the Raritan PHII toilet from the head. I also remove the pedestal on which the toilet was installed. You can see the outline of the pedestal around the large hole in the floor of the head through which the seawater intake and seawater outtake hoses were run. |
Old Toilet and Pedestal Removed from Head |
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Hole for Removed Sewage and Water Hoses |
This hole is in a platform above the cabin sole on which the toilet pedestal was secured to mahogany cleat stock. Removing the cleat stock turned out to be the most difficult part of the de-install. Removing the counter-sunk wood screws required a lot of pressure a Philips-head screw driver with the added leverage of a vice-locks wrench. The final two screws had to be drilled out. | ||||||||||||||||||||||||||||||||||||||||||||||||||
In the picture on the right I have placed the Airhead in what I expect will be its final location. I decided to wait over night before securing it to this position and then cutting the vent hose to length. |
Airhead Toilet in Place |
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Toilet Secured and Vent Hose Attached |
The next day I secured the brackets that hold the toilet in place to the toilet platform. I then cut the vent hose to length and attached it to the toilet bowl. | ||||||||||||||||||||||||||||||||||||||||||||||||||
Now the installation is basically complete. The big (and unpleasant) job that remains is to remove all of the water and sewage hoses from Sarah along with the LectraSan. This will be a messy and complicated job. To remove the LectraSan I will need to remove all of the water pumps (frig, A/C, shower) that currently reside just aft of the LectraSan. While I'm at it I will remove the low-volume seawater manifold and clean it up. | |||||||||||||||||||||||||||||||||||||||||||||||||||
I am a little concerned that these SS brackets will be strong enough to withstand the sideways force of someone (me at 250 lbs) sitting on the toilet when the boat is heeled or rolling. Other users have not reported problems in this area, which is why this is only a small concern. |
Bracket to Secure Airhead |
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Peat Moss Brick |
So
now the Airhead is operational. The brick of peat and the
enzyme package are on the counter, ready for the first use of the
toilet. Since I'm a regular guy, that should happen tomorrow
morning. Don't expect to see a report on how it went posted on this website. |
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No
need to avert your eyes from this picture. That is just the
crumbled up peat moss in the base of the toilet. This is not the correct way to use Peat Moss as I would learn later. It should be re-hydrated before being put in the bin. |
Peat Moss in Compost Bin |
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Learning To Live With Peat | |||||||||||||||||||||||||||||||||||||||||||||||||||
Well, once again I failed to carefully read and follow
instructions. As seen above I just crumbled the peat brick and
placed it in the composting chamber before my first use of the
toilet. The instructions clearly state that the peat must be
moisturized before putting it in the toilet. Without the moisture the peat does nothing to desiccate the waste, aid the composting and absorb the odors. After a few days of use the head had a very strong odor. The odor wasn't unbearable, but I had been told by the manufacturer and other users there is almost no odor from the toilet. I had expected only a very slight odor of peat. This definitely was not a slight odor and it definitely was not a peat odor, so something clearly was not working right. |
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Re-Hydrated Peat Moss |
After
an exchange of emails with the manufacturer and re-reading the
instructions I realized my error. I tried adding water to the
composting chamber, but that did not seem to help much. I
finally found a local source for the Sphagnum Peat bricks and I
hydrated the brick in a Zip-Loc bag as shown in the picture on the
left. This brick is only partially hydrated because it
would expand beyond to capacity of the 1 gallon bag if fully
hydrated. I've subsequently found that very large Zip-Loc bags will hold more than the contents of one hydrated brick of Peat Moss or COIR. |
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So I just added a few handfuls of peat to the composting chamber and
within minutes the odor had greatly diminished. By the next
day the odor was completely gone. I will keep adding water to
this bag adding more peat to the toilet until the entire brick is in
the chamber. |
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So I've ordered several bricks of COIR from a gardening website (http://www.gardeners.com/) and will use that peat in the future. | |||||||||||||||||||||||||||||||||||||||||||||||||||
Emptying the Airhead and Converting to COIR | |||||||||||||||||||||||||||||||||||||||||||||||||||
After nearly 10 weeks of live aboard use I finally emptied the
composting chamber, and this time recharged it with COIR instead of
Sphagnum. 10 weeks seems to be pretty consistent with other live aboards' experiences. Several couples have reported they average a little less than 6 weeks to fill the chamber. I am the only user of my Airhead. I probably could have gotten a couple of more weeks of use if I didn't have those large chunks of un-moisturized Sphagnum in the chamber because of my initial screw-up described above. For the re-charge I had several bricks of COIR on hand. I'm still working my way through the logistics of handling the compost material, and I am still making mistakes. Prior to emptying the compost chamber I placed one of the bricks in a 1 gallon Zip-Loc and added a couple of cups of water. This caused the COIR to expand to the limits of the Zip-Loc and I could not moisturize all of it. I took handfuls of the moisturized material and placed it in the emptied chamber. This was a little messy as it is difficult to hold the crumbly material in one's hand without letting lots of little pieces sprinkle about the head compartment. I also was not able to place enough material in the chamber for satisfactory use. I was having to moisturize the COIR a little at a time. So after a couple of uses the COIR in the chamber was over-whelmed and I was getting an unpleasant odor out of the vent. In a few days I got all of the material from a single COIR brick into the chamber and the odor disappeared. |
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I've revised my method for preparing the COIR. I placed another brick in a dry-wall-type bucket and added about 1/2 gallon of water. The COIR absorbed the moisture within a few hours and expanded to about 2 gallons in volume. I then placed the moisturized material in two 1 gallon Zip-Loc bags (shown in the picture on the right. Now I have a full brick of material ready to add to the chamber on the next re-charge. I also have material to add if more COIR is required on the current tank cycle. |
Hydrated COIR and COIR Bricks |
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My initial impression of on the use of COIR in place of Sphagnum is fairly neutral. COIR seems to work as well as Sphagnum, but it is a little more messy to handle. Unless there is a problem with the current cycle I'll stay with COIR. Also shown in the picture are two spare bricks of COIR that I purchased from Gardner's Supply (link above). | |||||||||||||||||||||||||||||||||||||||||||||||||||
Emptying the Urine Bottle | |||||||||||||||||||||||||||||||||||||||||||||||||||
Much more frequently than the compost bin, the Urine Bottle must be
emptied. While dumping the bottle overboard does not pollute
(Urine is sterile - no bacteria) it is generally not something other
people like to observe. It is also illegal in the U.S.A.
I suspect dumping urine was made illegal to take away the claim of a
person caught with an overboard discharging toilet, that they only
pump urine overboard. When at a marina I could take the bottle into the toilets and pour it down a commode or urinal. However that is often a long trek and won't be greeted any more enthusiastically by other persons in the toilets than the folks having cocktails in the cockpit of the boat in the next slip. |
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Urine Bottle Gauge |
So
my normal procedure is to check the urine level (gauge shown in the
picture on the left) each evening, after dark before going to bed.
If the bottle is more than 75% full I dump it overboard. Unfortunately the gauge, which is just vinyl hose, has become stained such that it is difficult to read the gauge. On more than one occasion I have checked the urine level before going to bed and decided it did not need to be dumped. The next morning I discovered that in fact the bottle was completely full. Now it's daylight and dumping the bottle overboard is a problem. I have a spare urine bottle for those incidents. |
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It is very important to prevent the bottle from filling to the top.
I let that happen just once. It is non-habit forming. Recently (Dec, 2008) I spent a month in a Florida marina where my boat was located in front of a popular bar/restaurant. My boat was illuminated by the lights from the bar and the marina. This made peeing off the deck or dock a very public event until well after midnight. It had also turned cold early in Florida and peeing off the deck at 3:00AM wasn't all that appealing even without the audience. So for nearly a month I was using the Airhead for almost every pee. I discovered that by myself, I could fill the bottle in less than 4 days. So, then I didn't really need the gauge, I just emptied the bottle every third night. FWIW, the urine level in the picture above is just barely on the bottom of the gauge. |
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After One Year (2009) | |||||||||||||||||||||||||||||||||||||||||||||||||||
Well, I've been using the Airhead for over a year now. That
included over 4 months anchored in the Bahamas with no choice of
using a marina facility. Even when I've been berthed in a
marina I've normally used the on board toilet, both because it is
more convenient and to fully exercise the toilet and find any
limitations. Overall I'm very satisfied with the decision to go with a composting toilet in general and the Airhead in particular. There really haven't been any serious gotcha's. Oh, I've let the urine bottle overflow once or twice and my experimentation with how much COIR to use still goes on, but it has really worked as advertised. Even my friend Steve Angst who crewed for me on the way to the Bahamas last year and for a week in the Abacos felt it was a good choice. There are several things I've learned in this year. |
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