A self-contained Sun-Mar composting toilet features a rotating drum and, below, a finishing chamber.
There hasn’t been a huge outcry from Madison residents demanding the right to install composting toilets.
The toilets, which turn solid waste into compost, are lauded by proponents because conventional toilets waste water with each flush. Older toilets use 3 to 7 gallons of water per flush, and even new low-flow toilets use 1.5 gallons per flush. According to the EPA, toilets account for the largest percentage of household indoor water usage.
But Madison does not allow composting toilets, period, says George Hank of building inspection. They violate both the health code (7.321) and the plumbing code (18.36). Basically, if there’s a sewer, you have to use it. The tiny house village on East Johnson Street initially wanted to use composting toilets, but were denied.
Dianné Aldrich of Monona fought to have a composting toilet allowed in the yurt she constructed in her backyard in 2008. She uses the yurt as a studio for her dance, Pilates and other classes.
“When I built it, I wanted to make as many green choices as possible,” says Aldrich, who is passionate about water conservation. She started the Lake Monona Water Walk in 2012 to raise awareness. “In a time of global water shortage, we’re flushing away potable water, decent water. It’s a crime,” she says.
Monona does not allow composting toilets per se, but Aldrich fought and received a variance by arguing that composting toilets don’t fall under Monona’s plumbing code because they don’t use water or require plumbing. The code is geared toward abolishing septic systems and outhouses in favor of modern sewage systems. Aldrich argued, moreover, that composting toilets aren’t producing waste that isn’t going into the sewer; they convert that waste into compost before it ever leaves the toilet.
Aldrich did a lot of research before she selected her self-contained model from Sun-Mar. She was so pleased with it, she became a local dealer for them.
Waste goes into a drum below the seat, along with bulking material and enzymes that aid in breakdown. Turning the drum also aids in breakdown. A fan evaporates urine and carries away odors — there’s less smell than conventional toilets, Aldrich says.
Most people use them in cabins, says Aldrich, but they’re also great for outbuildings like boathouses, or even “on a boat or in an RV.”
“They’re simple. Not much can go wrong,” she says, other possibly than with the fan. “But you can replace the fan without replacing the toilet.”
Aldrich says that while the resulting compost is safe to use on a vegetable garden, Wisconsin law requires that it be disposed of at a landfill. That might also seem a waste. But Aldrich says the toilet is so effective at reducing what goes into it, not much compost is generated anyway.