Top 12 things to know before buying a composting toilet 

Gain important knowledge, and avoid buying the wrong composting toilet. These 12 tips will help you avoid expensive mistakes.

The Thinktank has high capacity.

1. Will it stink inside? Absolutely not, as long as you have a toilet with a vent and fan. The fan draws air into the toilet, and exhausts the stinky air outside. It should never enter the bathroom area.
2. Will it stink outside? There can be a bit of odor where the vent terminates the home. This is less with a urine diverting toilet. The vent should not terminate near a deck, door, or opening window. If in doubt, run the vent up to the roof line. Do not believe anyone that tells you that you don’t need a vent. There is moist, stinky air in that toilet and it MUST go outside.
3. Does it have a view screen or trap door?  Surprisingly, many toilets do not have a view screen or trap door to conceal the solid waste. That means that every time you open the lid, you are staring at the last user’s poop! Ugh. No. The better toilets all have concealing view screens or trap doors that hide the waste from the user until opened.
4. Is it legal? Probably, but legality varies widely. Usually, permits can be obtained (if necessary) by approaching senior managers at the county office. Inspectors generally can’t approve them, because it’s not in the code book. You can read my detailed post on the subject here. Are Composting Toilets Legal?
5. Is it a urine diverting design? The better toilets separate urine from solids. Urine is practically sterile, and very easy to dispose of safely. Solids begin drying out quickly, lose odor, and also become easy to dispose of. When you combine urine and feces in one tank, it becomes much more difficult. You might need powerful heaters.
   

   Add a scoop of wood shavings before emptying. There should be no odor at all.

6. What do I do with the solid waste? You need to think about this carefully, because human waste can pollute the water and make people sick if not properly managed. Store the waste in a compost bin outside (I like the rotating bins). Ideally choose a bin that is sealed and cannot leach any liquid on to the ground (but is not airtight – there must be good ventilation). Ideally you will have 2 bins. Once the first bin is full (and that can take a year or more depending on the number of users), start using the second bin. When the second bin is full, the contents of the first bin can be placed on non edible plants.
7. How will I vent it? Vent it through the wall or roof. Most of what you need should be supplied with the toilet for a basic installation. Extra pipe can be purchased locally if needed.
8. How will I get rid of the urine? Urine can go into a gray water system (with the shower or sink water), or it can be drained into a rock pit, such as a French drain.
9. How often will I empty it? For two people: the smaller composting toilets for vans and RVs need to be emptied frequently. Probably every week or even more often. The larger toilets like the Thinktank will be emptied about every 3-4 weeks . This varies with the amount of toilet paper that is used, and whether of not a cover material is added.
10. Is there excellent service and support? Customer service and support is critical when buying a composting toilet. Make sure you can reach the appropriate people directly and easily. (This seems almost impossible these days). You will have questions. It’s best to buy from someone specializing in composting toilets, rather than a hardware store, or someone selling all kinds of products. You need expertise here. It’s critical to get the right toilet, and to install it properly.
11. Can men stand when using? Many toilets require men to sit when urinating. Some men will not do this.
12. Can insects get into the toilet? Most toilets are not tightly sealed, and it’s easy for small fruit flies to get inside, where they rapidly multiply. An airtight toilet is a better bet.

If you have other questions on composting toilets, please let me know.