Composting head options


When we first bought our Pacific Seacraft, Maria 31, the plumbing systems were in pretty bad shape, the head and black tank being the most serious issue. The previous owner had removed the original black tank and run a hose from the head to a collapsible five-gallon jug in the bilge. It was unsanitary and cringeworthy. Further inspection revealed that the old pump-out line had been semi-abandoned and stuffed into the space between the settee and the hull. The line was old and clogged by decades of dried-out waste. There was less than an inch of clearance and, should someone have been daft enough to try using it for its intended purpose, a crack in the line would have spewed sewage down along the inside of the hull and into the bilge. The whole setup needed to be replaced. 

At first we debated installing a traditional marine head. In order to do this, we would need a new black tank and pump-out line. Then we could look forward to all the unpleasantness that comes along with traditional marine heads. Odors can be controlled and minimized with chemical treatments, lots and lots of cleaning solutions and open port lights. But that often means time and effort refocused from enjoying the boat onto odor control. There is also the issue of extra chemicals being pumped into the ocean all in order to avoid nauseating smells. Even marine and ocean-safe cleaners can have an effect on the marine environment. 
Looking at alternatives
Deciding that a traditional marine head was probably not the best bet for us, we started looking at composting heads. There was a lot of conversation online about them but not many out on the water for us to look at. That being the case, research was our best solution. What we found was refreshing. Composting toilets don’t require a black tank or chemical treatments. Instead, the toilet is the storage unit. Since they trap all waste products within the toilet itself, the odor and mess of a traditional head is negated. In addition, they are very easy to install and require little maintenance other than the occasional emptying.

How it works is relatively simple. The composting head is an all-in-one fully functioning unit in which solids and liquids are stored and separated. Liquids are collected in a bottle toward the front of the head. The liquids bottle can be easily removed and poured out, either offshore or down a restroom drain. Solids are collected and composted separately in a drum under the lid of the head. A base of absorbent material like newspaper, husks or wood shavings is typically used as a composting starter. A handle is mounted on the side of the drum that stirs the solid material for aeration and effective decomposition. What little gas there is, is vented from the body of the drum to the exterior of the boat. The only difficulty in using a composting head is muscle control. Liquid and solid deposits need to be made separately for proper containment. No special cleaners or bowl treatments are needed. 

The head is mounted to the sole of the boat by a mounting plate and brackets. This plate holds the toilet in place and makes it possible for the drum and liquids bottle to be removed easily when necessary. Since there is no separate black tank and the collection bin is part of the unit, the head does sit a bit taller than a traditional marine head. This height difference must be taken into consideration when contemplating options. 

How often the head needs to be emptied depends entirely upon how often it is used. A full-time live-aboard may need to empty the bottle every other day, and the tank every other week. We are seasonal sailors and only need to empty the tank once a season and the bottle every other week. It is not very difficult or time consuming, though taking the head apart for the solids disposal does have a little bit of a learning curve. 

Three popular options
There are three primary manufacturers of composting marine heads: Air Head, Nature’s Head and C-Head. They all function in basically the same way, but each have a unique design and their own set of quirks. 

The Air Head option is perhaps the most popular composting toilet for boats, and it is the one we chose for our own. There are options for a marine or household seat size, which is very convenient considering the limited space of a typical sailboat head. From back to front the entire toilet is 18 inches deep. It stands an overall 20 inches tall. The solids tank sits in the base and is secured to the mounting bracket by two wing nuts. There are also two handles on the side of the tank to make lifting it out easier. The mixing handle sticks out from one side and, when considering placement, the full range of motion must be examined. The liquids bottle is held in place at the front of the unit with tabs that extend up from the mounting bracket. The seat is secured to the solids tank with wing nuts and sealed with a rubber gasket. There is a built-in funnel that directs the liquids away from the solids tank and to the liquids bottle at the front. 

This version of C-Head’s composting head has a teak enclosure and a tie-down capability. 

Courtesy C-Head

To empty the liquids bottle, simply unscrew the two wing nuts and lift the bottle away. The waste can be poured down a restroom drain or overboard if the vessel is far enough out to sea to comply with pump-out laws. To empty the solids tank, first remove the seat and lid by loosening the wing nuts at the front and top of the solids tank. Next, twist and lift the seat up and off the tank then set it aside. Unscrew the two wing nuts holding the tank in place and lift it out. Empty the solid waste into a garbage bag and dispose of it. 
The Air Head costs $1,029. This is a fully inclusive price and there are no additional pieces that must be purchased. Additional holding tanks and spare bottles can be purchased but are not necessary for initial setup. Visit the Air Head website,, for full specs and options. 

The Nature’s Head toilet is very similar in design, function and maintenance. The entire unit is 21 inches wide, 19 inches deep and 20 inches tall. There is an option for mixing handles that can reduce the width from 21 inches to 17 inches for conserving space. The unit overall, is a little bigger than the Air Head, but this allows for more stability. 

The solids tank is located under the seat and the liquids bottle is separate and at the front of the head. Rather than being secured in place by two wing nuts, the bottle sits in a tray that is integrated into the mounting plate, as does the solids tank. The seat is latched in place over the solids tank and rests atop the liquids bottle, further holding it in place. To empty the head, simply raise the latches on both sides of the seat and lift it away. The bottle can then be pulled out of the holding tray and emptied, as can the solids tank.  

For the Nature’s Head, prices start at $925 and can range up to $965, depending on handle and bottle options. There are no extra parts that need to be purchased for the installation and in a single afternoon this head can be set and ready for use. For more info visit Nature’s Head at  

The C-Head option is more common for off-the-grid housing and RVs, but they are made with marine applications in mind as well. This unit looks the most like a conventional toilet. The seat is a little larger and there are four different size options available depending on installation needs. All four models are 13.25 inches wide and 18 inches tall. The models range in depth from 18 inches to 15 inches, and have slightly different shapes for bulkhead and corner sets. 

As with the previous two models, the C-Head separates the solid and liquid waste. The primary difference is how this is done. The liquids are collected in a non-secured bottle set inside an inset within the housing of the unit. The design does not include a predesigned bottle but suggests using a milk jug or similar bottle. The solids tank is built into the C-Head housing and requires emptying every 10 to 15 uses. To empty, lift the lid and pull the collection tank or bottle out. 

The cost of a C-Head starts at $609 and, depending on options, can cost up to roughly $680. This does not include the mounting hardware or the liquids collection bottle. While this option is the least expensive it also requires a bit more effort to get ready. For more info visit C-Head’s website at  

Composting heads are safe for the environment, easy to use, clean and virtually odorless. There is no pump-out hassle, and disposing of waste is easy. For all these reasons, a composting head made the most sense for us. 

Sarah Moore is a mother, writer, adventurer, sailor, backpacker, and avid splasher of puddles. Her work has appeared in Maine Boats Homes & Harbors, Adventure Hats, The Sandy River Review and Doire Press.

By Ocean Navigator