Sun-Mar. The firm’s composting toilets evaporate urine and compost solid waste, so there’s no output or contamination of groundwater. The toilets use natural processes to convert waste into safe fertilizing soils and require no plumbing, water or septic system, or municipal sewage connection. Certified by the National Sanitation Foundation, the toilets are designed with constant fresh-air intake for odor-free operation, the company says. 888.341.0782. www.sun-mar.com.