Sun-Mar Excel Composting Toilet Review

Written by: Jamie

Updated on: September 25, 2021

The Sun-Mar Excel Composting toilet is an excellent choice for anyone that wants a top of the range composter that comes with the assurances of a big-name brand.

Sun Mar Excel Composting Toilet

Sun Mar Excel Review

The Excel is Sun-Mar’s best selling unit and one of the few toilets of this kind to be certified by the National Sanitation Foundation (NSF)


Sun Mar is a company that has a long history of composting toilets. In fact, Sun Mar holds a patent for the most effective way to compost, and so if you choose to purchase a Sun-Mar composting toilet, then you know you are getting something unique.

We want to give you all of the information to decide whether this is the right toilet for you.

By reading Sun Mar composting toilet reviews, you should be able to decide whether this the Excel model will meet your needs or whether you need to check out the other toilets in the Sun Mar range. 

Key Features

The Sun Mar Excel composting toilet comes with many great features as standard, and we have listed a range of them below for your information:

  • The Sun Mar Excel is a non-electric toilet that can be placed and used anywhere. It is a particularly great choice for anyone that wants to install a toilet away from the main house or if you are a fan of off-grid living.
  • There is zero water required to run this machine, and the waste is collected and stored in an odorless container, slowly composting until you are ready to use it once again.  
  • The compost processing handle makes it easy to process the compost over time, and the size of the toilet drum leaves you able to use the toilet for days without needing to empty it.
  • There is a four-inch vent at the back of the toilet that works to release the smell and neutralize it so that the air around the toilet is fresh and clean at all times.
  • The toilet uses a three-chamber system to turn the waste into compost. The first chamber is where fresh waste is deposited, and the second chamber is the evaporation chamber that creates the compost through heat and air movement. Finally, when the compost is ready for use, it moves into the finishing tray that is sealed away from the other chambers to avoid contamination.
  • The toilet completes the composting cycle so that you do not have to worry about moving it until it is completely ready for use in your garden.

When you purchase a Sun Mar, you will be amazed at the quality of the unit and the simplicity of the system.


The toilet is compact and capable of being used in a variety of locations. It’s a perfect height at 33 inches and is 22.5 inches wide and 33 inches deep. It has a pretty small footprint which makes it great for tight spaces.

Weighing in it only 90 lbs this could be an important factor for those that live life on the road.

The urine outlet is 32mm, and it is important, like with all composting toilets, that the urine section never encroaches onto the solid waste holder as the compost is likely to be too wet to compost properly.

Recommended: Don't miss our guide to Biolet compost toilets next.

Energy Consumption

The Sun Mar Excel can be used in either battery mode or as a solar-powered toilet; this makes it a great choice for off-grid properties that want access to a toilet no matter the energy supply.

The fan itself works off a 12V system, keeping the toilet smelling fresh at all times. The fan is an optional extra and is only advised for use if the toilet is installed with bends in the vent. 

How to Empty

The Sun Mar composting toilet has a one-inch drain that must be connected to a container for collection or a drain that can take the liquid away from the unit.

This makes it easy for any excess liquid to be taken away, but you can expect the toilet to evaporate liquid well, depending on how warm it is in its location.

When it comes to emptying the unit, you will need to remove the finishing drawer where you can take the compost and use it straight away.

The Sun Mar uses a three-chamber system that takes waste and gradually turns it into compost, meaning that when you remove the finishing drawer, you do not need to worry about it being contaminated with fresh waste.  

Recommended: Did the Excel make our list of recommendations?

Installation Procedure

When it comes to installing your new toilet and fan, you would be well advised to use the following tips so that you don't end up with any problems that need to be rectified after the toilet has been used for the first time.

The toilet is all ready to be taken out of the box and put where you are going to make use of it. As there are no electrics to wire up and no plumbing connections needed really is simple to prepare for use.

However, if you are also installing the vent, you need to keep the following tips in mind:

  • Remember to install your vents vertically.
  • Wherever possible, you should avoid bends in the vents, but if this is not possible, then do not have more than two bends, with no horizontal sections.
  • Remember that the vent needs to go higher than the peak of the roof!
  • It's well worth remembering that for decent air circulation, you should install the vent vertically, 2-3 feet above the top of the roof. This will allow any odors to be dispersed easily.

The Sun Mar Excel composting toilet has been built to make installation quick and easy so that it can be installed in a wide range of locations with ease.

Recommended: Don't miss our guide to the Separett Villa toilet.


  • No urine overflow
  • Odorless with unit's bacterial balance
  • Three-chamber system
  • Completes composting cycle


  • Potential base cracks
  • Might need an exhaust fan overtime

Bottom Line

If you need a reliable compost toilet then you won't go far wrong with the Sun-Mar Excel.

It's really easy to use and makes light work of the extra effort required when running a composting toilet system. It gets our seal of approval!

About the Author Jamie

I'm an English teacher and writer. I'm passionate about the environment and love the tiny house movement!

Share your thoughts

Your email address will not be published. Required fields are marked

{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}