It's as simple as 1-2-3
Back in the 60's Hardy Sundberg (Father of the present Sun-Mar partners) was trying to work out the best toilet set up for his cottage in Sweden. He started with an incinerating design, before finally concluding that maybe all he had to do was to help nature do it's own thing. The idea of a composting toilet was born.

Hardy put together all kinds of toilets, before he hit upon his gold medal design. The basic problem was, and still is, how do you optimize conditions for breaking down what we at Sun-Mar call "solid material," while ending up with a safe compost, evaporating the liquid, and producing no smell. The key turned out to be a composting drum. A place where you could keep the compost moist; retain the heat in the core of the compost, and achieve perfect mixing and aeration simply by rotating and tumbling the compost. Nothing too clever there you may say.

Sure, but Hardy still had to work out a few other pieces to the puzzle. How to make sure the compost didn't get too wet; how to make sure the waste went into the drum and stayed there; and how to extract compost from the drum. Hardy's solutions were pretty simple (some would say elegant). He cut a hole in the drum to receive the waste, and fitted a swinging door which closed automatically as the drum rotated for mixing, and opened automatically when rotated backwards for emptying. He put a screen at the rear of the drum to drain any excess liquid directly into an evaporating chamber. Finally he came up with the idea of a stopper which maintained the drum in a top dead center position to receive the waste, and allowed the drum to rotate backwards only when compost was being extracted.

The rest was much easier; He placed the second chamber, the compost finishing drawer, immediately below the door in the composting drum. That way compost falling directly into the drawer could be left in the drawer for completion of the composting process, and emptied only when more compost had to be extracted from the drum. Compost in this second chamber was isolated from liquid and surrounded by a stream of drying air. The evaporating chamber, the floor of the toilet, formed the third chamber, from where excess liquids not absorbed by the compost were evaporated. Hardy did this by pulling air through intake holes at the front of each side of the toilet, over the evaporating chamber, and up the vent stack. By so doing, he created a partial vacuum inside the toilet to ensure that there could be no smell under any circumstances.
In 1979, for Hardy Sundberg, the whole concept came together as easy as 1-2-3-.

It was so good we've spent the last thirteen years polishing it.

"SUN-MAR" is the first and only self contained composting toilet in the world to be
tested and certified by N.S.F. (The National Sanitation Foundation)

NSF Listed in Standard 41 - Sun-Mar Excel - 89

Electrical Features are CSA APPROVED LR 55925

Our founder's first composting toilet received a gold medal at
the International Inventor's Exhibition in Geneva, Switzerland.


    The HISTORY of "SUN-MAR" closely parallels the development of cottage toilets over the last 37 years.
  • 1966
    Our first cottage toilet (an incinerating design) was invented in Sweden.
  • 1971
    Abandoning incineration due to the high energy requirements, the first self contained composting toilet was developed in Switzerland by the Father of two SUN-MAR partners.
  • 1974
    Rights to the original composting toilet were sold, and the "TROPIC", a new design incorporation several improvements, was first produced in Sweden. (The rights to this unit were also sold when our superior technology outstipped its usefulness).
  • 1975
    Production moved to North America, and the WCM, the first central composting unit, was produced.
  • 1979
    First three chamber self contained toilet was introduced using a Bio-drum. (The forerunner of today's EXCEL unit).
  • 1981
    Bio-drum design proved so successful that a non- electric version (the EXCEL N.E.) was introduced.
  • 1987
    Non electric version of the WCM central composting unit (now known as the CENTREX N.E.) was added to the line.
  • 1989
    The SUN-MAR EXCEL became the first composting toilet to pass the long term composting tests of the National Sanitation Foundation.
  • 1991
    First dual vented unit (the EXCEL AD/DC) was marketed for those with a non continuous 110 Volt supply.
  • 1993
    SUN-MAR introduced the "COMPACT", a lower profile, more rounded unit with a patented variable diameter Bio- drum.
  • 1993
    The "CENTREX" family of lower profile, front vented central units was launched.


    The "ECOLET", the first self contained composting toilet ever designed for Marine and RV markets, was introduced


    Each year we have made small quality and performance improvements. Not so in 1994. There are no less than four significant improvements built into 1994 units, including a massive 56% increase in composting capacity.
    Bio-drum Capacity up by 56%
    As most of out dealers and users know, the secret to "SUN-MAR's" superior composting performance lies in the composing drum, - the Bio=drum. For the last 14 years, the tumbling action of this Bio-drum has allowed "Sun-Mar" to optimize composting performance by keeping the compost moist, oxygenated, mixed and warm. Now "SUN-MAR" engineers have found a way to increase usable Bio- drum capacity by an incredible 56% without increasing the size of the toilets!
    Sounds impossible? Here's how they did it. First, the drum was extended closer to both the front and back of the unit. Then, by relocating the drum lock mechanism they increased the diameter of the Bio-drum. Taken together these two changes increased available compost volume by an amazing 56%! For cottagers, the larger drum means that it should be unnecessary to extract compost during the season, almost regardless of how heavily the unit is use. For residential users, the larger volume means faster composting and less frequent removal of compost. Although "Sun-Mar" has made little change to maximum residential ratings, the larger drum now offers more spare capacity, which is especially important in residential applications. Introducing the Mixing Baffle
    All 1994 "SUN-MAR" units are fitted with a new, specially designed mixing baffle to optimize mixing. Now, when the drum rotates, not only is the tumbling action improved, but the baffle moves material from the front of the drum to the rear, and vice versa. The mixing action in the Bio-drum was very good before. It's now terrific!
    Here's to a Longer Fan Life
    Experience has shown that the fan is pretty well the only component in a "SUN-MAR" which is subject to failure. Two years ago we upgraded to a non-metallic bladed turbo-blower type fan. 1994 sees a further improvement by having a fan specially made to "SUN-MAR's" own specifications, which include dual ball bearings and a corrosion resistant stainless steel shaft. This 1994 upgrade will extend the service life, and eliminate stoppages caused by rust, and bearing "wobble".
    Do Not Touch!
    The push release mechanism we have used to prevent the Bio-drum from rotating backwards has been very reliable. The only drawback was that to release it, the user had to put a hand inside the unit. For reasons we at "SUN-MAR" don't understand, not everyone was thrilled by this arrangement! So, 1994 brings a change on all units. The old drum lock is replaced by an elegant pull release on the front of the drum. Outside the unit!
    Zero Block Drains Larger drains on all Central and Non-electric 1994 Models have removed any possibility of peat moss debris falling through the screen at the rear of the Bio-drum, and causing the drain to block.
    Electric Vent Stack Increase
    To reduce friction, and improve air movement, 1994 electric units are fitted with a 2" vent stack. This change will be particularly helpful where several 90 degree bends are necessary.


    Although the 1995 changes are not nearly as far reaching as those made in 1994, they represent some important improvements.

    Bigger Finishing Drawer
    A wider finishing drawer has been designed into all 1995 large drum units, (that's everything except the "COMPACT" and "ECOLET") so that 25 % more compost can be extracted at a time. This improvement has a direct bearing on composting capacity, because either intervals between extractions can be lengthened, or, if the same interval is maintained, more compost is extracted, and available capacity is increased.

    New Footrest
    A new footrest has been designed for all "EXCEL" family units, which, by being both narrower and shallower has a number of advantages over the previous footrest. The narrower design makes it easy for men to stand with their legs astride the footrest, while the shallower depth reduces the floor space requirement.
    New Bowl Liners
    Previously, bowl liners had been designed on the "one must fit all" principle. This resulted in a bowl liner design that was the lowest common denominator rather than the optimum design for each unit. In 1995 we have come close to optimizing the design by producing two different versions, one for the "COMPACT" and "ECOLET", and the other for the "EXCEL" family of units. As a result all self contained 1995 toilets will have greatly improved bowl liners.
    Drum Insulation
    In 1995, the composting drums on both non-electric units (EXCEL N.E." and "CENTREX N.E."), have been fitted with a high quality foam insulation to help maintain the heat developed in the compost, and so increase composting speeds. Insulation has also been fitted to all "CENTREX" family units because they are normally installed outside. .

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