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What is a Composting Toilet?

And Other Frequently Asked Questions

1. What is a composting toilet and how does it work?
2. Does a composting toilet smell bad?
3. What kind of composting toilets does the Composting Toilet Store sell?
4. Where can a composting toilet be installed?
5. Do I have to use a special kind of toilet paper?
6. Can baby wipes, tampons, diaper liners, paper towels, or other similar items be put in the toilet?
7. How do I clean the toilet?
8. Is it easy to operate? What kind of ongoing maintenance is required?
9. How do I know which composting toilet is right for me?
10. Is it difficult to install? Do I need a professional installer?
11. Will a composting toilet meet my local building code?
12. What kind of drains and/or water hookups do I need?
13. What if I don't have any electricity or water available in the location where I want to put the toilet?
14. What if I live on a slab, have no elevation, or want to install a toilet in my basement?
15. What do I do in the winter if I have no heat?
16. How and when will I need to remove finished compost? What do I do with it after it's removed?
17. What if the toilet gets clogged? Can I use a plunger?
18. Can I compost my kitchen scraps and/or yard waste in it, too?
19. Will I have a problem with methane gas or sewer gasses?
20. What is the expected life of a composting toilet?
21. What is the warranty?
22. What do I do if I need service or replacement parts?
23. What if I want to return the toilet? What is your return policy?


1. What is a composting toilet and how does it work?
First, a basic definition of "composting" may be helpful. Composting is simply the process of breaking down (or decomposing) organic matter. For example, in a garden composter, you put in yard waste such as leaves, grass clippings, and mulch, and eventually you get finished compost. Compost, also known as "black gold," is the most fertile substance you can use for planting, fertilizing, and amending soil. This is because it contains all the essential minerals and nutrients that plants need to grow and thrive.

Human waste can be composted just like any other organic matter. In fact, the composting process is even more rapid than in a garden composter, because our digestive systems have already done the majority of the breaking down process for us. Human waste is about 90% water, which means that one of the primary functions of a composting toilet is evaporation. Sun-Mar composting toilets feature a separate evaporation chamber where liquid is warmed (in electric units only) and evaporated with the assistance of a fan that is constantly moving air through the unit. Bulking material and microbes are added to break down the remaining minerals and what you are left with is a clean, dry, non-offensive compost---exactly the same end product as you would get from a backyard garden composter, or what you'd buy from a local nursery or garden center.

Composting Toilet

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2. Does a composting toilet smell bad?
Absolutely not. Our composting toilets are odorless for two reasons. First, sewer gasses are a byproduct of anaerobic composting, which means that the materials being broken down aren't aerated with ample oxygen. Our composting toilets all use aerobic composting as their method of breaking down waste. Aerobic microbes are very efficient, breaking down waste quickly, and most importantly, they do not put off methane or sulfate gasses in the decomposition process. Second, our composting toilets are designed to maintain a constant airflow through the unit, drawing air up and out through the vent stack. This airflow maintains a partial vacuum in the toilet, which guarantees odorless operation.

Want more proof? All of Sun-Mar's composting toilets are tested and certified by the National Sanitation Foundation, and the NSF will only certify composting units that produce no odor. To check for yourself, see Sun-Mar's NSF listing.

Click here to see customer reviews about odorless operation.

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3. What kind of composting toilets does the Composting Toilet Store sell?
The Composting Toilet Store is a dealer of Sun-Mar composting toilets. Sun-Mar is a Canadian company that has been developing and manufacturing composting toilets since 1971. Why have we chosen to sell only Sun-Mar units? That's simple. Sun-Mar is the world leader in composting technology. And most importantly, Sun-Mar composting toilets are the ONLY units certified by the NSF to comply with NSF/ANSI Standard #41 for residential and cottage use. This means they have been tested at maximum capacity and have been certified to operate odorlessly and produce a clean, dry finished compost. When you purchase a Sun-Mar, you are literally purchasing the standard in composting toilets.
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4. Where can a composting toilet be installed?
Anywhere you need a toilet. Composting toilets are very popular in cottages, cabins, pool houses, boat houses, and garden sheds. They can also be used in park shelters, remote offices or dormitories, barns, and security posts. Composting toilets are also frequently used in primary residences, in areas where there is a water shortage, or for those who simply don't want to spend the money to put in a septic system. The Composting Toilet Store even offers the MOBILE composting toilet, a unit specifically designed for installation on boats and RV's!
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5. Do I have to use a special kind of toilet paper?
No. You can use any type of toilet paper you want, the toilet will compost it without a problem.
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6. Can baby wipes, tampons, diaper liners, paper towels, or other similar items be put in the toilet?
No. We recommend keeping these and similar products out of the toilet because they can affect the capacity. When you choose a composting toilet, the most important consideration is the capacity rating. Our capacity ratings are stated as the number of people using the toilet per day. If you add other products to the toilet, this will throw off the capacity and can cause a problem.
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7. How do I clean the toilet?
The outside of the toilet can be cleaned using any type of regular household cleaner of your choosing. Around the rim of the bowl and inside the bowl of the toilet, we recommend using Compost Quick Cleaning Spray. This is a special toilet and bowl cleaner designed for composting toilets. It contains a compost accelerating agent that will aide in the breakdown process of your compost. If you don't want to use Compost Quick, you can also use a solution of hot water and baking soda. You should not use chemical toilet bowl cleaners in your composting toilet, because these products can kill the aerobic bacteria that are a vital part of the composting process.
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8. Is it easy to operate? What kind of ongoing maintenance is required?
Our composting toilets are very easy to operate. For ongoing operating, all you need to do is add Compost Sure or Compost Sure Blue to the Bio-Drum™ on a daily basis (the amount will vary depending on the type of unit you have; see product instruction manuals for specific information). Every 2-3 days while the unit is in use, pull out the drum handle and rotate the drum 4-6 times. If you're only using the unit on the weekend, simply rotate the drum when you arrive and again just before you leave. If your composting toilet is only being used seasonally, there are some basic startup procedures to be followed at the beginning of the season, and those are detailed in the Product Instruction Manuals available on each product detail page.
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9. How do I know which composting toilet is right for me?
There are several things to consider when choosing a composting toilet. First, how many people will be using the toilet each day? The answer to this question will likely impact whether you choose a self-contained unit or a central system. Second, do you want an electric or non-electric unit? And finally, do you want a water flush or waterless toilet? For help in selecting a composting toilet system that's right for you, please visit our Product Selection Guide.
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10. Is it difficult to install? Do I need a professional installer?
No. In most cases, Sun-Mar composting toilets are a do-it-yourself installation. Complete installation instructions can be found in the Product Instruction Manuals available on each product detail page. We encourage you to read these manuals thoroughly before purchasing a unit so that you will understand what is involved in installing your composting toilet before it arrives.
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11. Will a composting toilet meet my local building code?
In many communities, composting toilets are an already approved method of waste treatment and disposal. However, local building codes and regulations do vary, and in some communities, composting toilets simply haven't been "approved" yet. It is the consumer's responsibility to check with their local building department officials to be sure our composting toilets will meet their local regulations before buying and installing a unit. For more information about composting toilets and building codes, please visit our Building Codes section. There you'll find basic info about how building codes work in the United States, a list of building departments or government contacts, state by state, and links to other helpful organizations and resources. If you need detailed product information to take to your city officials for product approval, you can request a free catalog to be mailed to you. Please also feel free to contact us for additional information and recommendations.
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12. What kind of drains and/or water hookups do I need?
All our composting toilets feature a safety drain which we recommend hooking up on every installation. Even though Sun-Mar composting toilets will evaporate all liquids under normal conditions, there are some situations in which the safety drain might be needed. For example, if you have an electric toilet and you experience a prolonged power outage, the safety drain might be needed. Or if you have a non-electric unit, evaporating capacity can vary with humidity and other atmospheric conditions. In any case, it's always a good idea to hook up the safety drain just in case there is more liquid than the toilet can handle. The safety drain should be connected to an approved facility such as a recycling bed, old septic system, holding tank, or drain pit. For more details on hooking up the safety drain, please see the Product Instruction Manuals available on each product detail page.

Whether or not you will need to plumb in water lines is dependent upon the type of composting toilet system you choose. All our self-contained units are waterless, meaning that no plumbing is required. If you choose a water flush central system, you will need to hook up to water, though it is possible to also flush the unit manually with a container if necessary.
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13. What if I don't have any electricity or water available in the location where I want to put the toilet?
No problem. The Composting Toilet Store offers 13 different models of toilets that require no electricity and 12 models that use no water. For more assistance in selecting a non-electric and/or waterless composting toilet system that's right for you, please visit our Product Selection Guide.
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14. What if I live on a slab, have no elevation, or want to install a toilet in my basement?
In all of these cases, you would need to purchase a self-contained composting toilet. Please see our category of Self-Contained Units to review models that might work for you.
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15. What do I do in the winter if I have no heat?
For extended winter use, the composting unit has to be kept warm (specifically, warmer than 55 degrees Fahrenheit) for the microbes to remain active and composting to continue. It may be helpful to insulate vent piping on all units to avoid icing, and where applicable, also insulate inlet piping and drain piping. Electric units should remain plugged in to minimize the chance of freezing. To reduce energy costs, you might also want to consider installing a fan speed control on electric units. This reduces cold air intake and heater operation.

For limited winter use, it is okay to allow the compost to freeze. In this situation, the unit can be used as a holding tank, so long as there is enough space in the Bio-Drum™. It's important to remember that the drum should not be rotated if the compost is frozen, and if you have an electric unit, be sure to plug it in while in use so that the fan will eliminate any possible odors. For more details on winter use of your composting toilet, please see the Product Instruction Manuals available on each product detail page.
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16. How and when will I need to remove finished compost? What do I do with it after it's removed?
When the drum is half to 2/3 full, you'll need to remove some compost to the finishing drawer. This is a very quick and easy process, and no tools are needed. Simply release the drum lock, rotate the drum backwards, and some compost will drop automatically into the finishing drawer. The entire process takes less than a minute, and most importantly, you never come into contact with fresh material.

In the finishing drawer, compost will be isolated from contamination by fresh material. The compost should sit undisturbed in the finishing drawer for at least 4 weeks, or as long as you want. At that point, it will be sanitized and finished and can be removed at any time.

Composting Toilet

What do you do with finished compost? The finished product you get from your composting toilet will be a clean and dry compost that is sanitary. It is essentially the same finished product you would get out of a backyard garden composter, or the same product you'd go to a nursery or garden center to purchase. We recommend putting the compost on your flower garden or other landscaping area.
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17. What if the toilet gets clogged? Can I use a plunger?
The only type of composting toilet system that could feasibly get clogged would be a water flush central system, because these systems feature a more "traditional" looking toilet that is connected by 3" plumbing pipe to the central unit below. Should the toilet or pipe become clogged, a plunger can be used. You would need to keep the foot (flush) pedal depressed while using the plunger.
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18. Can I compost my kitchen scraps and/or yard waste in it, too?
We do not recommend composting kitchen scraps, yard waste, or any similar items in your composting toilet. First, adding anything besides human waste and toilet paper will adversely affect the capacity of the unit. When you choose a composting toilet, the most important consideration is the capacity rating. Our capacity ratings are stated as the number of people using the toilet per day. If you add other products to the toilet, this will throw off the capacity and can cause a problem. The other primary issue with adding food scraps and yard waste is that these items can potentially attract insects.

If you are looking for a way to compost kitchen scraps and yard waste, consider investing in a garden composter. Our sister site, Home Products 'n' More, offers a nice variety of compost tumbler bins that are designed for home composting, and all are available with free shipping and handling!
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19. Will I have a problem with methane gas or sewer gasses?
No. Methane and other sewer gasses are byproducts of anaerobic composting. This means that the material being broken down isn't exposed to enough oxygen for aerobic bacteria growth. All our composting toilets are designed to encourage aerobic composting through aeration of the contents of the Bio-Drum™. Every 2 or 3 days while the toilet is in use, you will pull out the drum handle (which is recessed on most self-contained units) and rotate the drum 4 to 6 times. This ensures that the aerobic bacteria have ample oxygen to do their job, and thus you won't have to worry about anaerobic composting that could create sewer gas.
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20. What is the expected life of a composting toilet?
The expected life of a Sun-Mar composting toilet is 20 to 25 years.
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21. What is the warranty?
All of our composting toilet systems are warranted by Sun-Mar for a period of 5 years on the shell and 3 years on other parts. For complete warranty details, please see our Warranty Information page.
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22. What do I do if I need service or replacement parts?
If you have a problem or need technical assistance with your toilet, please contact Sun-Mar directly at 888-341-0782, or you can feel free to contact us first, and we will have someone from Sun-Mar contact you directly. Sun-Mar provides excellent customer service and after-sales support, and they are the foremost experts in troubleshooting any installation difficulties or technical problems with your toilet system.

Service on the composting toilet systems is not included under warranty. If you do encounter a problem, the experts at Sun-Mar will walk you through any necessary steps to repair the unit or install replacement parts. Provided that the toilet system is installed correctly and used per the directions, there should be no need for service on the unit. Just following the standard procedures and regular maintenance as described in the Product Instruction Manuals is all you'll need to do.
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23. What if I want to return the toilet? What is your return policy?
We only accept returns of items that are brand new and have not been installed. For complete details, please visit our Return Policy page.
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