Thinking about installing a composting toilet? Conceptually, it might seem like a pretty cool idea. More advanced than a typical vault toilet, and more environmentally savvy. They can even generate useful agricultural bi-products in some situations.
However, there may be pitfalls (excuse the pun) to a composting toilet you are not aware of.
Under heavy use a composting toilet will require daily maintenance to work properly. Otherwise, the compost may turn septic and emit horrendous odors both inside and outside the cabin. This is not only an expensive problem to fix, but it also will take the restroom out of service for extended periods.
The cost and effort of daily maintenance becomes an issue in itself. Knocking down the fecal cone and removing debris from it is a dirty job that exposes employees to pathogens. Oxygen depletion in the basement can also be a concern.
Vigilant maintenance should result in composters working as advertised. However, a report by Gabrielle Pecora (on behalf of Thermopile Project) suggested that this outcome is unlikely. The case study analyzed 13 sites with composting toilets from 5 different manufacturers and found that “very few of these systems perform as they are advertised and require additional disposal costs including connection to local sewers, manual removal, or in some cases, system replacement.” Though not always a bad idea, composting toilets are a bit of a gamble with results that can be difficult to foresee.
Due to systematic failures over time, many compost toilet restrooms have been removed from service by their owners within their first 10 to 20 years of operation. As an example, the Colorado Department of Transportation installed several multi-million dollar composting restrooms at rest areas along Interstate 70. These have since been converted to flush restrooms at great expense. A composting toilet may not be your best long term solution.
Recently, I led a workshop on remote restroom options. I asked the group of about 60 participants “Who prefers any other kind of toilet to a flush toilet?” Not a single hand was raised. Having water in the toilet bowl with no direct visual link to human waste makes customers more confident the restroom is sanitary. Additionally, flush restrooms typically have a hand wash sinks – an option most composting toilets do not offer.
Composting and other waterless restrooms are meant for more remote situations where utilities are not available. But with Green Flush Technologies, a flush restroom can be placed almost anywhere. Offering more amenities than the spartan cabins of composters, it is surprising that our flush restrooms usually costs less per square foot than comparable composting toilets do.
After thousands of uses, our restrooms require periodic emptying of the sewage tank, typically under a contract with the same people who service the portable toilets. Contrast that with the daily maintenance that a composting toilet requires under heavy use.
For further reference on this subject see these articles.