Compost Toilets

The Secret to Sustainable Stool

While toilets aren’t something people are particularly fond of thinking about, take a moment to consider the amount of water and energy it takes to flush our human wastes away on average.

The average toilet accounts for about one-third of all household water usage. Older toilets use up to eight gallons of water per flush, while toilets made since 1994 use 1.6 gallons per flush. Considering that the average person flushes around five times a day, the average household wastes a considerable amount of potable water.

However, there are options that can not only save water, but help nourish plants in the end. According to Recode, an Oregon based non-profit that helps create sustainable legislature, composting toilets might just be the future of sustainable stool.

Toxic Waste 
Corvallis, the heart of the “Grass Seed Capital of the World,” is no stranger to the smell of freshly spread manure. Animal manure contains nitrogen that plants need for growth – and human manure (a.k.a. “humanure”) is no exception. Until recently, with the invention of our modern sewer system, human waste was a naturally occurring fertilizer in the environment.

With common flush toilets, the propagation power of our excreta is all but lost, as the nitrogen is instead released into our water system, where it feeds algae instead of plants. Our current systems treat water to a certain degree, but in the process, nitrogen gets diluted and becomes difficult to extract. It gets pumped back into oceans, rivers, and lakes with the treated water, a process linked to harmful algae blooms in all 50 states. These algae blooms choke out fish, are toxic to people and animals, and are generally devastating to the environment.

Because composting toilets don’t use water when flushing, all the energy that would be expended by a flush toilet, from the septic system to the treatment plant, is saved. The more people that use compost toilets, the more our waterways would improve. One online article examples the Chesapeake Bay, where about 1.5 billion gallons of wastewater from about 500 sewage treatment plants enter every day, leaving much of the water a dead zone, uninhabitable to plants and animals.

Compost Benefits 
Composting toilets can lower a household’s toilet water consumption by up to 100 percent. Some composting toilets use no water at all, while others use very little. For example, the Clivus Multrum Foam Flush toilet uses only 6 ounces of water per flush, more than 95 percent less than the standard 1.6 gallons per flush. Composting toilets can also cut a household’s nitrogen output by up to 96 percent and may save more than 6,600 gallons of water per person a year.

Instead of using water to flush, composting toilets simply use gravity and a collection/compost chamber to turn human “manure” into a fertilizer which is clean and safe to spread on gardens and plants.

For the most part, microbes do all of the work for you, although it is important to add sawdust, wood chips, or other organic material such as grass clippings to begin the composting process. The addition of these materials also helps trap gasses and add a pleasant odor. Online reviews and literature explain that compostable toilets are less likely to cause a stink, due to negative pressure mechanisms that pull the air down as soon as the lid is lifted.

Toilet paper is also an acceptable addition, but generally takes longer to decompose than other organic material. Studies have shown that toilet paper made out of recycled paper typically breaks down quicker, along with less substantial types of toilet paper such as RV and septic-safe papers.

Composting toilets have to meet a certain National Sanitation Foundation standard (NSF 41) to be able to be installed legally. This standard requires that the product be performance tested for a minimum of six months. Some of the products that meet these standards are: Clivus Multrum, Sunmar, Envirolet, and Advanced Composting Toilet Systems.

For Your Household
Although there is technically no “plumbing” in composting toilets, the easiest way to install one in your home, while supporting local businesses, is to call your local plumber. Evenflo Plumbing on Reservoir Avenue is currently providing estimates for composting toilet installs and will be happy to answer any questions. Evenflo can help you choose what designs are best for your needs, and provide an estimate after a consultation and evaluation of your current plumbing system. Otherwise, some composting toilet producers, such as Advanced Composting Toilet Systems, offer to install a unit for a price.

Though worth the expense, these toilets can cost anywhere from $900 to $5,000 for a higher-end unit. Alternatively, you can build your own composting toilet; Recode Oregon has been working with the state to ensure that site-built composting toilets are legal in most jurisdictions.

In the long run, whether you buy or build your composting toilet, having one will save you money by reducing water usage, save thousands of gallons of potable water, and reduce your environmental footprint, all while creating a valuable fertilizer.

Recode Oregon is kicking off its 100 year water vision for the state of Oregon, to help create equitable and sustainable water legislation. They will be holding educational sessions around the state to introduce topics like composting toilets and listen to any concerns or questions you might have. For more information or consultation about building your own toilet, contact Recode at, where you can sign up for their online newsletter.

By Lydia Parker