The Excel is not only our best-selling unit, but also the first self-contained composting toilet to be certified by NSF (National Sanitation Foundation) in 1989. Since then, there have made many modifications to improve performance in all three chambers - evaporation, composting, and finishing. When you purchase an Excel, you are purchasing the composting toilet that sets the standard.

The Excel is ideal for residential use having been tested by NSF with 4 adults using the unit residentially for six months of continual use. In this test, the criteria were that the unit operated odorlessly and produced clean, safe compost. Of course, it did, and the Excel is presently the ONLY self-contained unit in the world to be tested, certified, and listed by NSF.

The Excel is also ideal for cottage use as the primary toilet at your camp or cabin, or for light commercial or workplace use. The 2" vent is attached at the top back of the unit and can be installed invisibly by running it through the wall and up the outside wall. For comfort the Excel has a sturdy detachable footrest which can be removed to pull out the finishing drawer.

Although the Excel can normally evaporate all liquids, a ½" emergency drain is fitted at the rear and this should be connected if the unit is to be used residentially or heavily, or if prolonged power outages are expected.

Frequently Asked Questions About Composting Toilets

How much odor comes from a composting toilet?

None. Air is being continuously drawn in to the unit and up the vent stack, creating a partial vacuum in the unit. In addition, the composting drum fosters a good aerobic compost which produces no odors.

How often do you empty it?

Never completely. You typically empty some of the compost out of the drum once per year for cottage use, once every few months for residential use. In cases of continuous use, you may extract some compost more often. This always sits in the drawer to cure before being removed - you are never handling any fresh waste when the unit is properly operated.

Do I add any chemicals?

No. The only thing that is added is peat moss mixed with wood shavings, (60% wood shavings, 40% peat moss, or Sun-Mar's Compost Sure peat mix with hemp). Chemicals are, in fact, dangerous to the composting process and should never be added at all.

What happens in the winter?

Nothing. The compost remains in the drum and freezes, so no composting is taking place. The elements will NOT damage the system during the winter months. In fact, waste can be added in limited quantities during the winter for use as a holding tank, if you are only planning to use the unit about once a month.

Can it be used all winter?

Yes. If the area where the composting unit is heated to a minimum 55 degrees Fahrenheit throughout the winter, then composting will occur.

How much hydro do they use?

About 150 Watts. The electric units require hydro to power a fan (30 Watts continuous) and a heating element that is thermostatically controlled. The average draw is about 150 Watts, or the equivalent of a lightbulb. Larger models may have larger power requirements.

What if no electricity is available?

No problem. Each Sun-Mar toilet is available in a non-electric version.

I have a generator that runs part of the time. Can I use an electric unit?

No. A non-electric unit is recommended or a unit that has both electric and non-electric capabilities (AC/DC unit).

How do you clean it?

You only have to clean the bowl (in a central system) or the bowl liner (self-contained unit) as you would a regular bowl, except without the use of chemicals. Recommended cleaners are Sun-Mar Compost Quick or hot water that is mixed with baking soda or vinegar.

Does the Fiberglass used in your composting toilets smell?

Does the fiberglass used to make the body of your car smell? No. Off gassing from the fiberglass production process does produce an odor, but it is gone by the time that the toilet is built and boxed.

What kind of plastics do you use in your production?

We use high quality, recyclable, cold-resistant plastics. Sun-Mar engineers use the best materials for each part of the design. We find that this produces a better product than using one material throughout.

How Do You Get the Most Capacity out of a Composting Toilet System?

Different sizes of drums. Common sense tells us that more people means more waste, and for more waste we need a bigger composting vessel. Sun- Mar is the only company that offers a larger solution for a larger problem.

Why does no-one else use a drum inside a composting toilet?

They can’t. Many of our drum design features are patented.

Do animals harm the system?

No. The compost is not something that is attractive to animals. Some people do build an enclosure to ensure curious animals or children don't tamper with the units.

What is the warranty?

The warranty is 25 years on the fiberglass shell and 3 years on all other parts.

What parts wear out?

Like brakes or tires on a car, certain parts eventually need to be replaced. On Sun-Mar toilets, the fan and the thermostat usually fail after a number of years. In both cases the parts are inexpensive and are easily accessible for you to repair.

Is the Fan Noisy?
The fan on our AC models is just as noticeable as an oscillating room fan in terms of noise level. If you are concerned about fan noise being a problem, you can purchase a fan speed control with your unit that will allow you to turn down the fan speed, and therefore the noise, whenever you like.

You may have heard from users of older Sun-Mar units (pre-1998) that their fans were noisy. They were noisier than the current model, as the fan was from a different manufacturer and of an entirely different design. Just another example of how we are always improving your composting toilet experience.

On a central system, how far away from the toilet bowl can the composting unit be located?

Up to 15 feet is usually safe. We have encountered cases that have had longer distances, but in every case we recommend that you carefully follow installation instructions. It is very important that you carefully measure the slope of the pipe in any case.

How many toilets can I hook up to a central system?

You may connect up to 3 toilets to any one system. The amount of toilets is not as important as the number of people using the system.


Can you throw the paper in the toilet?

Yes. The paper is a source of carbon for the compost. You do not need to buy special toilet paper to use in our system, as a properly operating compost will break down regular toilet paper in a short period of time. Of course single ply will break down faster, but it is not necessary - and anybody who tells you it is is probably trying to sell you fancy expensive toilet paper!


Should males still urinate outside or in the outhouse?

No. In fact, the liquid is beneficial to the composting process.

How Do I Dispose of my Kitchen and Bathwater Waste ?

This is an answer that changes with each installation. There are two things to consider. The first, and most important, is what you are legally allowed to do. If you contact your local Department of Health, or building inspector, they should be able to tell you exactly what is legal to do in your area.