Little Muss, No Flush

By Christina Birchfield | 11/13/2013

Composting Toilets. Are we there yet?

 

Someday in the future people may ask, “You used drinkable water for what? Were you crazy?”

In the days of flush water resources, potable water used to flush away waste became commonplace.Even with low-flow toilets, some 30 percent of potable drinking water is used for flushing toilets in the United States, according to the Watershed Management Group. Now common at highway rest stops, composting toilets have also been becoming more commonplace in areas such as the Chesapeake Bay Foundation and in Tucson, Ariz., at the Watershed Management Group’s (WMG’s) Living Lab and Learning Center.

The Chesapeake Bay Foundation’s composting toilets have been in service for years and come complete with a porcelain throne and apparatus below the toilets for composting. The foundation uses Clivus Multrum composting toilets, “the grandfather” of composting toilets,” available in the United States since 1972. However, not all municipalities and local governments approve of composting toilets. NutriCycle Systems says the Clivus Multrum is the “easiest brand for obtaining Health Department approval.” Nutricycle Systems was the composting toilet contractor for The Chesapeake Bay Foundation headquarters.

In Tucson, Ariz., the Watershed Management Group (WMG) is working with University of Arizona on a two-year demonstration project to making permitting and installation of composting toilets easy.

The composting toilet model being tested at the WMG’s Living Lab and Learning Center on North Dodge Boulevard is far more prosaic than units used in rest stops and at the Chesapeake Bay Foundation. Those plumbing fixtures look like traditional fixtures.

The Tucson version being tested are barrel composting toilets. The toilets featured at the Living Lab is a series of three barrels for collecting waste, some pipe fitting for vents and the toilet seat placed in an outhouse. When a barrel fills, the owner shifts the toilet seat to the next barrel. Remarkably, though not too far beyond the outhouse concept of a hole in the ground or a porta-potty, there was no adverse smell. The WMG personnel showing us the toilet did say that as composting occurred as the barrel filled, the area below the seat could feel quite warm.

WMG’s Web site, explains the project: “To make the composting toilet solution an alternative that’s more accessible to homeowners, WMG engaged with a diverse committee of stakeholders, including the Arizona Department of Environmental Quality (ADEQ), to obtain experimental permits to build, use, and test four types of site-built composting toilets. In contrast with currently permissible systems, the toilets are all made from locally-available materials, with costs to build and install them starting at about $350.” This is about one-third the cost of commercially-available composting toilets.

So far, there are 18 composting toilet participants in Tucson. The University of Arizona has a team including scientists and anthropologists that is helping WMG with the project. Professor of Environmental Microbiology Charles Gerba in the U of A’s Department of Soil, Water and Environmental Science will be testing the finished compost.

Once approved by local municipalities, composting toilets could be doubly useful in desert environs: Composting toilets could preserve potable water, a diminishing resource in face of continuing drought. The finished compost can enhance desert soils to help grow plants and hold soil moisture. Food scraps can already by legally composted. Composting does require a balance of nitrogen, carbon, moisture and heat. Composting toilet waste requires sawdust or plant material for balance. Heat, a natural part of composting, destroys pathogens. Compost must be stirred to keep the process active. Some of the expensive commercial toilets do the stirring automatically.

Just for fun here is a game about toilets of the world—the Crapper Mapper. It shows bathrooms and toilet stalls around the globe. The multiple choice answers are interactive: correct answers hear a flush, incorrect answers hear a ruder sound.

 

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