Installing a Sun-Mar Composting Toilet

What Comes with the Toilet?

Our systems come as a complete package ready for installation as per the prices quoted on this site. You will receive every component you need to complete the installation.

Who can Install and the Tools Required?

If the toilet is to be installed in Australia or New Zealand as part of a building application with council approval a plumber is generally required to sign off on the installation. Sun-Mar also has the Centrex models with the 500ml flush option so if this is your model of choice it is strongly recommended that you use a plumber to install the system. If you don't have a plumber or builder in mind we can also recommend one who has experience with our Nature Loo systems.

 That said, our waterless toilets can be installed in half a day by anyone who has access to the tools listed below. So if you aren't seeking council's approval of the system then simply follow the DIY instruction manual for the composting toilets and greywater system.  Tools and material required:

  • Phillips & Flathead screwdriver
  • Electric drill with a hole saw bit
  • Jigsaw
  • Wire cutters
  • PVC non-pressure pipe glue
  • Silicone
  • Shovel (for bathtub sized absorption trench)

For all Sun-Mar models, 240v and 12v models, you do not need an electrician for the installation itself. However, if you are using mains power to run the fan you will need to ensure a power point is located near the ventilation pipe. If the fan is to be solar powered then follow the instructions in the manual on connection to the solar regulator.

Placement of the Toilet Pedestal

Sun-Mar "split" systems (e.g. the Centrex range) 

The Sun-Mar Centrex split systems require a clear space below the bathroom floor or a lower level to the side of the house to where the compost treatment chamber can be located.

A 500ml microflush pedestal option is available where multiple toilets can be connected to a single Centrex unit. The compost Bio-drum/chamber does not need to be directly beneath the pedestals. The chamber can be located to the side of the house as long as the waste pipe is angled down and gravity can move the waste along the pipe. This allows more flexibility with the location of the compost chamber and toilet pedestals.


The composting chamber should be installed on the north side of a home to maximize exposure to direct sunlight. The Centrex should be positioned on a leveled concrete slab with a slight lean to the liquid drain outlet. You will need to have access to the compost treatment chamber to add bulking mix and rotate the drum.

Sun-Mar "self-contained" systems (e.g. the Excel range & Compact)

Self-contained units are very compact with the Bio-drum compost treatment chamber held inside the toilet pedestal. The handle to rotate the compost chamber and finishing tray where the treated compost is removed are hidden in the front of the unit (see maintenance for more details). The capacity of these systems is reduced compared with split systems but they can be installed directly on the floor.

The 240-volt models come with a heater and powerful 35-watt fan that can evaporate all liquid if continuous power can be guaranteed and the recommended number of users is not exceeded. These systems can be installed in rooms that do not have access to the outside. However, an emergency liquid drain connection is recommended.


Ventilation System

As with all composting toilets, the heart of the system is the 12 or 240-volt fan which runs the Ventilation System 24 hours a day to continuously circulate air through the compost heap.
The air is drawn down through the toilet pedestal through the compost chamber and out of the vent pipe.  This set-up ensures that no odours enter the toilet room.

Vent pipe (4") and connections are provided. Further lengths can be supplied should you not have sufficient pipe to extend at least 600mm above the highest point of your roof.


      - Using Mains Power

240-volt models: Australian pin plug is provided that can be connected to a mains power point

12-volt models: 240/12 volt regulated transformer, extension wire, and connectors are all included as standard to run the fan from mains power.

      - Using our Solar Kit

If you have purchased our 20 or 40 Watt Solar System  you will have all the components required to complete your installation. The 4m of external double insulated cable and 4m of standard cable provided should be sufficient to locate your panel where will be best to capture the sun. However, if you think you will require additional cabling please let us know. 

      - Using Your Existing Solar Power

If your house is powered by solar, you will have a battery bank that will generally be either 12-volt or 24-volt DC.  If you have a 12-volt system, just connect the battery directly to the fan.  Don’t forget to put a 0.5 amp fuse in line with the fan.

If you have a 24-volt system, ask us for a 24-volt fan which will allow you to run the fan directly from your 24-volt battery bank.  The fan will use about 6 amp-hours of power on a 12-volt system.

If you have an inverter, don’t use it. The inverter will run very inefficiently when it is powering only the small fan and you will waste a lot of precious power.  It may even flatten your batteries.

Excess Liquid Absorption Trench

The liquid discharge connection must be permanently connected to a small absorption trench as depicted below. This is the standard requirement as per AS/NZS 1546.2.


All models are supplied with a length of flexible 25mm drain hose. You may need to buy a length of 50mm PVC pipe to connect the hose to the slotted ag pipe in the absorption trench. The length will depend on where you choose to put the trench.


Contact Info

6 Hurricane Street
Banyo QLD, 4014

Call us
1300 138 182
07 3889 6144


Maintaining a Sun-Mar Composting Toilet

Any cleaning? Not as much as you’d think


The waterless and microflush toilet pedestal are designed to be cleaned less often than a standard 4-6L flushing toilet. The microflush pedestal has a self-cleaning ball valve that generally takes care of the job for you. Cleaning of the toilet seat itself is done with a natural cleaning product called Nature Flush. The product's enzymatic action also helps compost break down and eliminates odours. The enzymes are supplied as a concentrate where 1L of concentrate is diluted to 20L of Nature Flush. A bottle of Nature Flush concentrate and a spraying flask are provided with the toilet in the starter pack. Additional refills of the concentrate can be purchased on this website or over the phone at a later date.

The spray can also be used in the evaporation chamber at the bottom of a system where every 3 months (if the system is used full-time) the small rake provided should be used to remove any debris in the evaporation tray at the bottom of the unit .


Adding bulking agent/mulch & rotating the Bio-drum


These are the only activities you will have to do on a regular basis when it comes to maintaining your Sun-Mar composting toilet system. You will need to add bulking material (approximately a cupful per person per day) and rotate the drum. Sample bags of the bulking material (sugarcane mulch) are provided with the toilet and can be sourced from landscape/garden supply stores. Peat moss can be added to the bulking agent to increase the moisture level if the compost is drying out too quickly.

Removal of Compost

The drum rotation is a periodic task which ensures that, when it comes time to empty the compost, you can be assured you will have produced nice compost. The handle of the Bio-drum on the Centrex, Excel and Compact should be rotated clockwise every second day when the toilet is in use. You will need to anti-clockwise when it is approximately half full. This will empty a portion of the compost into the finishing drawer. It is best to leave the compost in the finishing drawer for approximately 7 weeks so that the compost can continue to process.

The installation and maintenance manual provided with the toilet outlines these activities and we also provide customer support Monday to Friday on 1300 138 182  or 07 3889 6144 should you have any questions unanswered in this material.

Contact Info

6 Hurricane Street
Banyo QLD, 4014

Call us
1300 138 182
07 3889 6144